9029 Commits
Author SHA1 Message Date
Ido Schimmel 791c91dc7a ipv6: mcast: Fix use-after-free when processing MLD queries
When processing an MLD query, a pointer to the multicast group address
is retrieved when initially parsing the packet. This pointer is later
dereferenced without being reloaded despite the fact that the skb header
might have been reallocated following the pskb_may_pull() calls, leading
to a use-after-free [1].

Fix by copying the multicast group address when the packet is initially
parsed.

[1]
BUG: KASAN: slab-use-after-free in __mld_query_work (net/ipv6/mcast.c:1512)
Read of size 8 at addr ffff8881154b8e90 by task kworker/4:1/118

Workqueue: mld mld_query_work
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
print_address_description.constprop.0 (mm/kasan/report.c:378)
print_report (mm/kasan/report.c:482)
kasan_report (mm/kasan/report.c:595)
__mld_query_work (net/ipv6/mcast.c:1512)
mld_query_work (net/ipv6/mcast.c:1563)
process_one_work (kernel/workqueue.c:3314)
worker_thread (kernel/workqueue.c:3397 kernel/workqueue.c:3478)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:158)
ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
</TASK>

[...]

Freed by task 118:
kasan_save_stack (mm/kasan/common.c:57)
kasan_save_track (mm/kasan/common.c:78)
kasan_save_free_info (mm/kasan/generic.c:584)
__kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285)
kfree (./include/linux/kasan.h:235 mm/slub.c:2689 mm/slub.c:6251 mm/slub.c:6566)
pskb_expand_head (net/core/skbuff.c:2335)
__pskb_pull_tail (net/core/skbuff.c:2878 (discriminator 4))
__mld_query_work (net/ipv6/mcast.c:1495 (discriminator 1))
mld_query_work (net/ipv6/mcast.c:1563)
process_one_work (kernel/workqueue.c:3314)
worker_thread (kernel/workqueue.c:3397 kernel/workqueue.c:3478)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:158)
ret_from_fork_asm (arch/x86/entry/entry_64.S:245)

Fixes: 97300b5fdf ("[MCAST] IPv6: Check packet size when process Multicast")
Reported-by: Leo Lin <leo@depthfirst.com>
Reviewed-by: David Ahern <dahern@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://patch.msgid.link/20260603101811.612594-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-04 08:50:33 -07:00
Jiayuan Chen f723ccaff2 ipv6: anycast: insert aca into global hash under idev->lock
syzbot reported a splat [1]: a slab-use-after-free in
ipv6_chk_acast_addr(), which walks the global inet6_acaddr_lst[] hash
under RCU and dereferences a struct ifacaddr6 that has already been
freed while still linked in the hash, so a later reader walks into a
dangling node.

In __ipv6_dev_ac_inc() the aca is allocated with refcount 1, then
aca_get() bumps it to 2 to keep it alive across the unlocked region.
It is published to idev->ac_list under idev->lock, but
ipv6_add_acaddr_hash() runs after write_unlock_bh(). A concurrent
teardown (ipv6_ac_destroy_dev() from addrconf_ifdown(), under RTNL)
can slip into that window:

  CPU0 __ipv6_dev_ac_inc           CPU1 ipv6_ac_destroy_dev (RTNL)
  ------------------------------   ------------------------------------
  aca_alloc()              refcnt 1
  aca_get()               refcnt 2
  write_lock_bh(idev->lock)
    add aca to ac_list
  write_unlock_bh(idev->lock)
                                   write_lock_bh(idev->lock)
                                     pull aca off ac_list
                                   write_unlock_bh(idev->lock)
                                   ipv6_del_acaddr_hash(aca)
                                     hlist_del_init_rcu() is a no-op,
                                     aca is not in the hash yet
                                   aca_put()           refcnt 2->1
  ipv6_add_acaddr_hash(aca)
    aca now inserted into the hash
  aca_put()                refcnt 1->0
    call_rcu(aca_free_rcu) -> kfree(aca)

The hash removal becomes a no-op because the insertion has not
happened yet, so once CPU0 inserts and drops the last reference, the
aca is freed while still linked in inet6_acaddr_lst[], and readers
dereference freed memory after the slab slot is reused.

This window opened once RTNL stopped serializing the join path against
device teardown. Move ipv6_add_acaddr_hash() inside the idev->lock
section so the ac_list and hash insertions are atomic with respect to
teardown: a racing remover now either misses the aca entirely or finds
it in both lists.

acaddr_hash_lock is now nested under idev->lock, which is acquired in
softirq context, so switch all acaddr_hash_lock sites to spin_lock_bh()
to avoid the irq lock inversion reported in [2].

[1] https://syzkaller.appspot.com/bug?extid=a01df04303c131efbf3a
[2] https://lore.kernel.org/netdev/6a194ef7.ba3b1513.1890b4.0000.GAE@google.com/

Reported-by: syzbot+819eb928d120d2bdad0e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/6a191f87.ce022c6e.138e56.0003.GAE@google.com/T/
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Fixes: eb1ac9ff6c ("ipv6: anycast: Don't hold RTNL for IPV6_JOIN_ANYCAST.")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260529152219.235475-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-02 19:30:39 -07:00
Jiayuan Chen 36d29ceec3 netfilter: nft_fib_ipv6: bail out of sibling walk if rt got unlinked
This was reported by Sashiko [1].

The RCU walk over rt->fib6_siblings can spin forever if rt is unlinked
mid-iteration: rt->fib6_siblings.next still points into the old ring,
so the loop never meets &rt->fib6_siblings as its terminator.

fib6_purge_rt() always does WRITE_ONCE(rt->fib6_nsiblings, 0) before
list_del_rcu(), so readers can use rt->fib6_nsiblings == 0 as the
detach signal. The same pattern is used in fib6_info_uses_dev() and
rt6_nlmsg_size().

[1]: https://sashiko.dev/#/patchset/20260520023411.391233-1-jiayuan.chen%40linux.dev
Suggested-by: Florian Westphal <fw@strlen.de>
Fixes: 1c32b24c23 ("netfilter: nft_fib_ipv6: switch to fib6_lookup")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-06-01 13:43:52 +02:00
Fernando Fernandez Mancera 072aa0f5c3 Revert "ipv6: preserve insertion order for same-scope addresses"
Chris Adams reported that preserving insertion order for same-scope
addresses is causing SSH connections to be dropped after stopping a VM
while running NetworkManager.

NetworkManager caches the IPv6 address configuration, when a RA arrives,
it determines the list of addresses to configure and checks if the
addresses are already in the right order in the kernel. If they aren't,
NetworkManager removes and re-adds them to achieve the desired order.

As the order changes, NetworkManager is confused and reconfigures the
addresses on every update. In addition, this would also affect to cloud
tooling that relies on IPv6 addresses order to identify primary and
secondaries addresses.

This reverts commit cb3de96eea.

Fixes: cb3de96eea ("ipv6: preserve insertion order for same-scope addresses")
Reported-by: Chris Adams <linux@cmadams.net>
Closes: https://lore.kernel.org/netdev/20260521135310.GC977@cmadams.net/
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260529112357.5079-1-fmancera@suse.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-29 13:00:54 -07:00
Jakub Kicinski c84ff04def Merge tag 'ipsec-2026-05-29' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec
Steffen Klassert says:

====================
pull request (net): ipsec 2026-05-29

1) xfrm: route MIGRATE notifications to caller's netns
   Thread the caller's netns through km_migrate() so that
   MIGRATE notifications go to the issuing netns, fixing both the
   init_net listener leak and MOBIKE notifications inside
   non-init netns. From Maoyi Xie.

2) xfrm: ipcomp: Free destination pages on acomp errors
   Move the out_free_req label up so that allocated destination
   pages are released on decompression errors, not only on success.
   From Herbert Xu.

3) xfrm: Check for underflow in xfrm_state_mtu
   Reject configurations that cause xfrm_state_mtu() to underflow,
   preventing a negative TFCPAD value from becoming a memset size
   that triggers an out-of-bounds write of several terabytes.
   From David Ahern.

4) xfrm: ah: use skb_to_full_sk in async output callbacks
   Convert the possibly-incomplete skb->sk to a full socket pointer
   in async AH callbacks so that a request_sock or timewait_sock
   never reaches xfrm_output_resume() downstream consumers.
   From Michael Bommarito.

5) Add and revert: esp: fix page frag reference leak on skb_to_sgvec failure
   The patch does not fix te issue completely.

6) xfrm: esp: restore combined single-frag length gate
   Check the aligned post-trailer combined length against a page limit
   in the fast path, preventing skb_page_frag_refill() from falling
   back to a page too small for the destination scatterlist.
   From Jingguo Tan.

7) xfrm: iptfs: reset runtime state when cloning SAs
   Reinitialise the clone's mode_data runtime objects before
   publishing it, preventing queued skbs from being freed with
   list state copied from the original SA when migration fails.
   From Shaomin Chen.

8) xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit
   Flush policy tables and drain the workqueue in a .pre_exit handler
   so that cleanup_net() pays one RCU grace period per batch instead
   of one per namespace, fixing stalls at high CLONE_NEWNET rates.
   From Usama Arif.

9) xfrm: input: hold netns during deferred transport reinjection
   Take a netns reference when queueing deferred transport reinjection
   work and drop it after the callback completes, keeping the skb->cb
   net pointer valid until the deferred work runs.
   From Zhengchuan Liang.

* tag 'ipsec-2026-05-29' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec:
  Revert "esp: fix page frag reference leak on skb_to_sgvec failure"
  xfrm: input: hold netns during deferred transport reinjection
  xfrm: move policy_bydst RCU sync from per-netns .exit to .pre_exit
  xfrm: iptfs: reset runtime state when cloning SAs
  xfrm: esp: restore combined single-frag length gate
  esp: fix page frag reference leak on skb_to_sgvec failure
  xfrm: ah: use skb_to_full_sk in async output callbacks
  xfrm: Check for underflow in xfrm_state_mtu
  xfrm: ipcomp: Free destination pages on acomp errors
  xfrm: route MIGRATE notifications to caller's netns
====================

Link: https://patch.msgid.link/20260529092648.3878973-1-steffen.klassert@secunet.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-29 12:57:23 -07:00
Jiayuan Chen 9c7da87c2d ipv6: fix possible infinite loop in fib6_select_path()
Found while auditing the same pattern Sashiko reported in
rt6_fill_node() [1]. Apply the same fix as
commit f8d8ce1b51 ("ipv6: fix possible infinite loop in fib6_info_uses_dev()").

Writers holding tb6_lock can list_del_rcu(&first->fib6_siblings)
without waiting for RCU readers; first->fib6_siblings.next then
still points into the old ring and this softirq-side walker never
reaches &first->fib6_siblings as its terminator. fib6_purge_rt()
always WRITE_ONCE()s first->fib6_nsiblings to 0 before
list_del_rcu(), so an inside-loop check is a reliable detach signal.

[1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev

Fixes: d9ccb18f83 ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260527053133.180695-2-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-29 12:41:00 -07:00
Jiayuan Chen 9f72412bcf ipv6: fix possible infinite loop in rt6_fill_node()
Sashiko reported this issue [1]. Apply the same fix as
commit f8d8ce1b51 ("ipv6: fix possible infinite loop in fib6_info_uses_dev()").

Writers holding tb6_lock can list_del_rcu(&rt->fib6_siblings)
without waiting for RCU readers; rt->fib6_siblings.next then still
points into the old ring and this softirq-side walker never reaches
&rt->fib6_siblings, causing a CPU stall. fib6_del_route() always
WRITE_ONCE()s rt->fib6_nsiblings to 0 before list_del_rcu(), so an
inside-loop check is a reliable detach signal.

[1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev

Fixes: d9ccb18f83 ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260527053133.180695-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-29 12:40:05 -07:00
Steffen Klassert 6851161feb Revert "esp: fix page frag reference leak on skb_to_sgvec failure"
This reverts commit 2982e599ff.

The patch does not fully fix the issue and the Author does
not match the 'Signed-off-by:' tag, so revert it for now.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-05-29 10:23:25 +02:00
Rahul Chandelkar 9d5e7a46a9 ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
ipv6_rpl_srh_decompress() computes:

    outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);

hdrlen is __u8. For n >= 127 the result exceeds 255 and silently
truncates. With n=127 (cmpri=15, cmpre=15, pad=0, hdrlen=16):

    (128 * 16) >> 3 = 256, truncated to 0 as __u8

The caller in ipv6_rpl_srh_rcv() then places the compressed header
at buf + ((ohdr->hdrlen + 1) << 3). With hdrlen=0 this is buf + 8,
but the decompressed region occupies buf[0..2055] (8-byte header
plus 128 full addresses). The compressed header overlaps the
decompressed data, and ipv6_rpl_srh_compress() writes into this
overlap, corrupting the routing header of the forwarded packet.

The existing guard at exthdrs.c:546 checks (n + 1) > 255, which
prevents n+1 from overflowing unsigned char (the segments_left
field), but does not prevent the computed hdrlen from overflowing
__u8. n=127 passes because 128 <= 255, yet hdrlen=256 does not
fit.

Tighten the bound to (n + 1) > 127. This caps n at 126, giving
hdrlen = (127 * 16) >> 3 = 254, which fits in __u8. The compressed
header then lands at buf + ((254 + 1) << 3) = buf + 2040, exactly
past the decompressed region (buf[0..2039]). No overlap. 127
segments is well beyond any realistic RPL deployment.

Fixes: 8610c7c6e3 ("net: ipv6: add support for rpl sr exthdr")
Signed-off-by: Rahul Chandelkar <rc@rexion.ai>
Link: https://patch.msgid.link/20260525154031.2290876-1-rc@rexion.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-27 19:05:53 -07:00
Qi Tang dd433671fe ipv6: validate extension header length before copying to cmsg
ip6_datagram_recv_specific_ctl() builds IPV6_{HOPOPTS,DSTOPTS,RTHDR}
cmsgs (and their IPV6_2292* legacy counterparts) by trusting the
on-wire hdrlen byte (ptr[1]) when computing the put_cmsg() length.
The length was validated only at parse time (ipv6_parse_hopopts(),
etc.).  An nftables payload-write expression can rewrite hdrlen after
parsing and before the skb reaches recvmsg; the write itself is
in-bounds but put_cmsg() then reads up to ((hdrlen+1) << 3) = 2040
bytes from an 8-byte header.  nftables is reachable from an
unprivileged user namespace, so this is an unprivileged
slab-out-of-bounds read:

  BUG: KASAN: slab-out-of-bounds in put_cmsg+0x3ac/0x540
   put_cmsg+0x3ac/0x540
   udpv6_recvmsg+0xca0/0x1250
   sock_recvmsg+0xdf/0x190
   ____sys_recvmsg+0x1b1/0x620

Add ipv6_get_exthdr_len() which validates that at least two bytes
are accessible before reading the hdrlen field, then checks the
computed length against skb_tail_pointer(skb), returning 0 on
failure.  Extension headers are kept in the linear skb area by
pskb_may_pull() during input, so skb_tail_pointer() is the correct
bound.

Use ipv6_get_exthdr_len() at all non-AH call sites: the five
standalone cmsg blocks (HbH, 2292HbH, 2292DSTOPTS x2, 2292RTHDR)
and the three standard cases in the extension-header walk loop
(DSTOPTS, ROUTING, default).  AH retains an inline bounds check
because its length formula differs ((ptr[1]+2)<<2).

The walk loop also gets a pre-read bounds check at the top to
validate ptr before any case accesses ptr[0] or ptr[1].

When the walk loop detects a corrupted header, return from the
function instead of continuing to process later socket options.

Cc: stable@vger.kernel.org
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Qi Tang <tpluszz77@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260523143245.2281415-1-tpluszz77@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-26 18:53:10 -07:00
Maoyi Xie 8b484efd5c ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().
After patch 1/2 in this series, vti6_update() unlinks and relinks
the tunnel through t->net. vti6_siocdevprivate() still uses
dev_net(dev) for the collision lookup. For a tunnel moved through
IFLA_NET_NS_FD, dev_net(dev) is the new netns, not t->net.

SIOCCHGTUNNEL on a migrated tunnel then runs:

  net = dev_net(dev)                    /* migrated netns */
  t   = vti6_locate(net, &p1, false)    /* misses target in t->net */
  ...
  t   = netdev_priv(dev)
  vti6_update(t, &p1, false)            /* mutates t->net's hash */

A caller in the migrated netns picks params that match a tunnel
in the creation netns. The lookup in dev_net(dev) finds nothing.
vti6_update() prepends the migrated tunnel at the head of the
creation netns hash bucket for those params. Later lookups in
the creation netns resolve to the migrated device. xfrm receive
delivers the matched packets through a device the caller controls.

Reachable from an unprivileged user namespace (unshare --user
--map-root-user --net). Cross tenant scope on container hosts.

Switch the SIOCCHGTUNNEL path on a non fallback device to use
t->net for the lookup. The lookup now matches the netns
vti6_update() operates on.

Also add ns_capable(self->net->user_ns, CAP_NET_ADMIN) before
the lookup. The check at the top of the case is against
dev_net(dev)->user_ns, which after migration is the attacker's
netns. A caller there can pick params absent from self->net,
the lookup returns NULL, t becomes self, and vti6_update()
inserts the device into the creation netns hash. The new check
requires CAP_NET_ADMIN in the creation netns user_ns too.

SIOCADDTUNNEL and SIOCCHGTUNNEL on the fallback device keep
dev_net(dev), which equals init_net there.

Fixes: 61220ab349 ("vti6: Enable namespace changing")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Suggested-by: Xiao Liang <shaw.leon@gmail.com>
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Link: https://patch.msgid.link/20260521130555.3421684-3-maoyixie.tju@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-26 11:16:12 +02:00
Kuniyuki Iwashima 11b326fb0a ip6: vti: Use ip6_tnl.net in vti6_changelink().
ip netns add ns1
ip netns add ns2
ip -n ns1 link add vti6_test type vti6 remote ::1 local ::2 key 7
ip -n ns1 link set vti6_test netns ns2
ip -n ns2 link set vti6_test type vti6 remote ::3 local ::4 key 9
ip netns del ns2
ip netns del ns1
[  132.495484] ------------[ cut here ]------------
[  132.497609] kernel BUG at net/core/dev.c:12376!

Commit 61220ab349 ("vti6: Enable namespace changing") dropped
NETIF_F_NETNS_LOCAL from vti6 devices. A vti6 tunnel can then
move through IFLA_NET_NS_FD. After the move dev_net(dev) points
at the new netns while t->net stays at the creation netns.

vti6_changelink() and vti6_update() still use dev_net(dev) and
dev_net(t->dev). They unlink from one per netns hash and relink
into another. The creation netns is left with a stale entry.
cleanup_net() of that netns later walks freed memory.

Reachable from an unprivileged user namespace (unshare --user
--map-root-user --net). Cross tenant scope on container hosts.

Fixes: 61220ab349 ("vti6: Enable namespace changing")
Reported-by: Maoyi Xie <maoyi.xie@ntu.edu.sg>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260521130555.3421684-2-maoyixie.tju@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-26 11:16:12 +02:00
Justin Iurman d47548a366 ipv6: exthdrs: refresh nh pointer after ipv6_hop_jumbo()
ipv6_hop_jumbo() calls pskb_trim_rcsum(), which can change skb pointers.
Let's recompute nh pointer to make sure any change won't mess things up.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Justin Iurman <justin.iurman@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260522112013.12342-1-justin.iurman@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-25 11:08:00 -07:00
Zhengchuan Liang f7b52afe35 ipv6: exthdrs: refresh nh after handling HAO option
ip6_parse_tlv() caches skb_network_header(skb) in nh while walking
IPv6 TLVs.

ipv6_dest_hao() may call pskb_expand_head() for a cloned skb, which can
move the skb head and invalidate the cached network header pointer.
Refresh nh after ipv6_dest_hao() returns so any trailing padding or TLVs
are parsed from the current skb head.

This matches the existing pattern used in ip6_parse_tlv() after helpers
that can modify skb header storage.

Fixes: a831f5bbc8 ("[IPV6] MIP6: Add inbound interface of home address option.")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Co-developed-by: Luxing Yin <tr0jan@lzu.edu.cn>
Signed-off-by: Luxing Yin <tr0jan@lzu.edu.cn>
Signed-off-by: Zhengchuan Liang <zcliangcn@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Reviewed-by: Justin Iurman <justin.iurman@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/7aba1debc2196189172499e5769802b026f8caf8.1779247873.git.zcliangcn@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-25 11:07:40 -07:00
Jiayuan Chen f81b0c2d28 netfilter: nft_fib_ipv6: handle routes via external nexthop
fib6_info has a union:

    union {
        struct list_head fib6_siblings;
        struct list_head nh_list;
    };

Old-style multipath (ip -6 route add ... nexthop ... nexthop ...) uses
fib6_siblings.  External nexthop (ip -6 route add ... nhid N) uses
nh_list, linked into &nh->f6i_list.

nft_fib6_info_nh_uses_dev() blindly walks &rt->fib6_siblings, causing
an OOB read past the struct nexthop slab when rt->nh is set:

  ==================================================================
  BUG: KASAN: slab-out-of-bounds in nft_fib6_eval+0x1362/0x16c0
  Read of size 8 at addr ffff888103a099d0 by task ping/386

  CPU: 2 UID: 0 PID: 386 Comm: ping Not tainted 7.1.0-rc3+ #251 PREEMPT
  Call Trace:
   <IRQ>
   dump_stack_lvl+0x76/0xa0
   print_report+0xd1/0x5f0
   kasan_report+0xe7/0x130
   __asan_report_load8_noabort+0x14/0x30
   nft_fib6_eval+0x1362/0x16c0
   nft_do_chain+0x279/0x18c0
   nft_do_chain_ipv6+0x1a8/0x230
   nf_hook_slow+0xad/0x200
   ipv6_rcv+0x152/0x380
   __netif_receive_skb_one_core+0x118/0x1c0
  ==================================================================

Branch by route shape: when rt->nh is set, walk via
nexthop_for_each_fib6_nh() (also covers nh groups, which the original
code missed); otherwise walk fib6_siblings, guarded by READ_ONCE() of
rt->fib6_nsiblings as required by commit 31d7d67ba1 ("ipv6: annotate
data-races around rt->fib6_nsiblings").

Fixes: 1c32b24c23 ("netfilter: nft_fib_ipv6: switch to fib6_lookup")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22 12:28:46 +02:00
Jiayuan Chen 1d001b0a61 netfilter: nft_fib_ipv6: walk fib6_siblings under RCU
nft_fib6_info_nh_uses_dev() runs from nft_fib6_eval() in softirq under
rcu_read_lock().  fib6_siblings is modified by writers that hold
tb6_lock but do not wait for RCU readers, so the sibling walk should
use list_for_each_entry_rcu(): it adds READ_ONCE() on the ->next
pointer and lets CONFIG_PROVE_RCU_LIST validate the locking.

No functional change for non-debug builds.

Fixes: 1c32b24c23 ("netfilter: nft_fib_ipv6: switch to fib6_lookup")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Florian Westphal <fw@strlen.de>
2026-05-22 12:28:46 +02:00
Jingguo Tan dfa0d7b0ff xfrm: esp: restore combined single-frag length gate
The ESP out-of-place fast path appends the trailer in esp_output_head()
before esp_output_tail() allocates the destination page frag. The
head-side gate currently checks skb->data_len and tailen separately, but
the tail code allocates a single destination frag from the combined
post-trailer skb->data_len.

Reject the page-frag fast path when the combined aligned length exceeds a
page. Otherwise skb_page_frag_refill() may fall back to a single page while
the destination sg still spans the combined skb->data_len.

Restore this combined-length page gate for both IPv4 and IPv6.

Fixes: 5bd8baab08 ("esp: limit skb_page_frag_refill use to a single page")
Cc: stable@vger.kernel.org
Signed-off-by: Lin Ma <malin89@huawei.com>
Signed-off-by: Chenyuan Mi <michenyuan@huawei.com>
Signed-off-by: Jingguo Tan <tanjingguo@huawei.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-05-22 09:20:26 +02:00
e521588 2982e599ff esp: fix page frag reference leak on skb_to_sgvec failure
In esp_output_tail(), when esp->inplace is false, the old skb page frags
are replaced with a new page from the xfrm page_frag cache. The source
scatterlist (sg) is built from the old frags before the replacement, and
esp_ssg_unref() is responsible for releasing the old page references
after the crypto operation completes.

However, if the second skb_to_sgvec() call (which builds the destination
scatterlist from the new page) fails, the code jumps to error_free which
only calls kfree(tmp). The old page frag references captured in the
source scatterlist are never released:

  1. sg[] is built from old frags via skb_to_sgvec() (no extra get_page)
  2. nr_frags is set to 1 and frag[0] is replaced with the new page
  3. Second skb_to_sgvec() fails -> goto error_free
  4. kfree(tmp) frees the sg[] memory but old frags are not unref'd
  5. kfree_skb() only releases frag[0] (the new page), not the old ones

Fix this by adding a bool parameter to esp_ssg_unref() that, when true,
unconditionally unrefs the source scatterlist frags without checking
req->src and req->dst, since those fields are not yet initialized by
aead_request_set_crypt() at the point of the error. Existing callers
pass false to preserve the original behavior.

The same issue exists in both esp4 and esp6 as the code is identical.

Fixes: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a ("esp6: Avoid skb_cow_data whenever possible")

Signed-off-by: Alessandro Schino <7991aleschino@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-05-22 09:19:37 +02:00
Justin Iurman e46e6bc97f ipv6: ioam: refresh hdr pointer before ioam6_event()
Reported by Sashiko:

In ipv6_hop_ioam(), the hdr pointer is initialized to point into the
skb's linear data buffer. Later, the code calls skb_ensure_writable(),
which might reallocate the buffer:

	if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))
		goto drop;

	/* Trace pointer may have changed */
	trace = (struct ioam6_trace_hdr *)(skb_network_header(skb)
					   + optoff + sizeof(*hdr));

	ioam6_fill_trace_data(skb, ns, trace, true);

	ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev),
		    GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);

If the skb is cloned or lacks sufficient linear headroom,
skb_ensure_writable() will invoke pskb_expand_head(), which reallocates
the skb's data buffer and frees the old one, invalidating pointers to
it. While the code recalculates the trace pointer immediately after the
call to skb_ensure_writable(), it fails to recalculate the hdr pointer.

This patch fixes the above by recalculating the hdr pointer before
passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

Fixes: f655c78d62 ("net: exthdrs: ioam6: send trace event")
Cc: stable@vger.kernel.org
Signed-off-by: Justin Iurman <justin.iurman@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260520124242.32320-1-justin.iurman@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-21 08:19:25 -07:00
Yuho Choi 1341db3224 ipv6: route: Unregister netdevice notifier on BPF init failure
ip6_route_init() registers ip6_route_dev_notifier before registering the
IPv6 route BPF iterator target. If bpf_iter_register() fails after the
notifier has been registered, the error path currently jumps to
out_register_late_subsys and unwinds the RTNL handlers and pernet route
state without removing the notifier from the netdevice notifier chain.

This leaves ip6_route_dev_notify() callable after the IPv6 route state it
uses has been torn down. Add a separate unwind label for the BPF iterator
failure path and unregister the netdevice notifier before continuing with
the existing cleanup.

Fixes: 138d0be35b ("net: bpf: Add netlink and ipv6_route bpf_iter targets")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260520030329.1061183-1-dbgh9129@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-21 07:43:15 -07:00
Eric Dumazet 1bbf0ced1d tcp: fix stale per-CPU tcp_tw_isn leak enabling ISN prediction
Blamed commit moved the TIME_WAIT-derived ISN from the skb control
block to a per-CPU variable, assuming the value would always be consumed
by tcp_conn_request() for the same packet that wrote it. That assumption
is violated by multiple drop paths between the producer
(__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer
(tcp_conn_request()):

 - min_ttl / min_hopcount check
 - xfrm policy check
 - tcp_inbound_hash() MD5/AO mismatch
 - tcp_filter() eBPF/SO_ATTACH_FILTER drop
 - th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN
 - psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()
 - tcp_checksum_complete() in tcp_v{4,6}_do_rcv()
 - tcp_v{4,6}_cookie_check() returning NULL

When a packet is dropped on any of these paths, tcp_tw_isn is left set.

The next SYN processed on the same CPU then consumes the non zero value in
tcp_conn_request(), receiving a potentially predictable ISN.

This patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu
variable.

Note that tcp_v{4,6}_fill_cb() do not set it.

Very litle impact on overall code size/complexity:

$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7)
Function                                     old     new   delta
tcp_v6_rcv                                  3038    3042      +4
tcp_v4_rcv                                  3035    3039      +4
tcp_conn_request                            2938    2923     -15
Total: Before=24436060, After=24436053, chg -0.00%

Fixes: 41eecbd712 ("tcp: replace TCP_SKB_CB(skb)->tcp_tw_isn with a per-cpu field")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260519084611.2485277-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-20 19:14:06 -07:00
Justin Iurman d4ea0dfd75 ipv6: ioam: add NULL check for idev in ipv6_hop_ioam()
Reported by Sashiko:

The function ipv6_hop_ioam() accesses
__in6_dev_get(skb->dev)->cnf.ioam6_enabled without validating the returned
idev pointer. Because addrconf_ifdown() can concurrently clear dev->ip6_ptr
via RCU, __in6_dev_get() can return NULL during interface teardown, which
could cause a NULL pointer dereference when processing an IOAM Hop-by-Hop
option.

Let's add a check and use SKB_DROP_REASON_IPV6DISABLED accordingly.

Fixes: 9ee11f0fff ("ipv6: ioam: Data plane support for Pre-allocated Trace")
Cc: stable@vger.kernel.org
Signed-off-by: Justin Iurman <justin.iurman@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260517183059.29140-1-justin.iurman@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-19 18:46:44 -07:00
Zhengchuan Liang 4322dcde6b netfilter: ip6t_hbh: reject oversized option lists
struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors,
but hbh_mt6_check() does not reject larger optsnr values supplied from
userspace.

Validate optsnr in the rule setup path so only match data that fits the
fixed-size opts array can be installed. This follows the existing xtables
pattern of rejecting invalid user-provided counts in checkentry() and
keeps the packet matching path unchanged.

`struct ip6t_opts` has a fixed `opts[IP6T_OPTS_OPTSNR]` array,
where `IP6T_OPTS_OPTSNR` is 16, then off-by-one array access is possible:

[  137.924693][ T8692] UBSAN: array-index-out-of-bounds in ../net/ipv6/netfilter/ip6t_hbh.c:110:29
[  137.926167][ T8692] index 16 is out of range for type '__u16 [16]'

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Zhengchuan Liang <zcliangcn@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2026-05-16 13:21:41 +02:00
Michael Bommarito 79d8be2623 xfrm: ah: use skb_to_full_sk in async output callbacks
When AH output is offloaded to an asynchronous crypto provider
(hardware accelerators such as AMD CCP, or a forced-async software
shim used for testing), the digest completion fires
ah_output_done() / ah6_output_done() on a workqueue.  The egress
skb at that point may have been originated by a TCP listener
sending a SYN-ACK, which sets skb->sk to a request_sock via
skb_set_owner_edemux(); it may also have been originated by an
inet_timewait_sock retransmit.  Neither is a full struct sock, and
passing the raw skb->sk to xfrm_output_resume() then forwards a
non-full socket through the rest of the xfrm output chain.

xfrm_output_resume() and its downstream consumers expect a full
sk where they dereference at all.  The natural egress path
through ah_output_done() does not crash today because the
consumers that read past sock_common are either gated by
sk_fullsock() or short-circuit on flags that are clear on a fresh
request_sock; an exhaustive walk of the 50 most plausible
consumers under sch_fq, dev_queue_xmit, netfilter, tc-egress and
cgroup-egress BPF found no current unguarded deref.  The bug is
still a real type confusion that future consumer changes could
turn into a memory-corruption primitive.

This is the same bug class fixed for ESP in commit 1620c88887
("xfrm: Fix the usage of skb->sk").  Apply the analogous fix to
AH: convert skb->sk to a full socket pointer (or NULL) via
skb_to_full_sk() before handing it to xfrm_output_resume().

The same async AH callbacks were touched recently for an
independent ESN-related ICV layout bug in commit ec54093e6a
("xfrm: ah: account for ESN high bits in async callbacks"); the
sk type-confusion addressed here is orthogonal.  This patch is
part of an ongoing audit of the AH callback paths; an ah_output
ihl-validation hardening series is also currently under review on
netdev.

Reproduced under UML + KASAN + lockdep with a forced-async
hmac(sha1) shim that registers at priority 9999 and wraps the
sync in-tree hmac-sha1-lib.  With the shim loaded, ah_output_done
runs on every SYN-ACK egress through a transport-mode AH SA and
skb->sk arrives as a request_sock (TCP_NEW_SYN_RECV); after this
patch, xfrm_output_resume() receives the listener (the result of
sk_to_full_sk()) and consumer derefs land on full-sock fields as
intended.

Fixes: 9ab1265d52 ("xfrm: Use actual socket sk instead of skb socket for xfrm_output_resume")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-05-16 10:56:14 +02:00
Jakub Kicinski 28d0060632 Merge tag 'nf-26-05-08' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf
Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following batch contains Netfilter fixes for net:

1) Allow initial x_tables table replacement without emitting an audit
   log message. Delay the register message until after hooks are wired up
   to avoid unnecessary unregister logs during error unwinding.

2) Fix a NULL dereference by allocating hook ops before adding the
   table to the per-netns list. Use `synchronize_rcu()` during error
   unwinding to ensure the table stops processing packets before
   teardown. Defer audit log register message until all operations
   succeed.

3) Refactor xtables to use a single `xt_unregister_table_pre_exit`
   function. Eliminate code duplication by centralizing table
   unregistration logic within the xtables core. ebtables cannot be
   changed due to incompatibility.

4) Unregister xtables templates before module removal. This prevents
   a race condition where userspace instantiates a new table after the
   pernet unreg removed the current table.

5) Add `xtables_unregister_table_exit` to fully unregister netfilter
   tables during module removal. Unlink the table from dying lists,
   then free hook operations.

6) Implement a two-stage removal scheme for ebtables following the
   x_tables pattern. Assign table->ops while holding the ebt mutex to
   prevent exposing partially-filled structures.

7) Fix ebtables module initialization race. Register the template last
   in table initialization functions. Prevent table instantiation before
   pernet operations are available.

8) Fix a race condition in x_tables module initialization. Ensure
   pernet ops are fully set up before exposing the table to userspace.

9) Fix a race condition in ebtables module initialization, similar to
   previous patch.

10) Restore propagation of helper to expected connection, this is a
    fix-for-recent-fix.

11) Validate that the expectation tuple and mask netlink attributes are
    present when adding expectation via nfqueue, this fixes a possible
    null-ptr-deref.

12) Fix possible rare memleak in the SIP helper in case helper has been
    detached from conntrack entry, from Li Xiasong.

13) Fix refcount leak in nft_ct when creating custom expectation, also
    from Li Xiason.

Patches 1-9 from Florian Westphal.

10) Restore propagation of helper to expected connection, this is a
    fix-for-recent-fix.

11) Check that tuple and mask netlink attributes are set when creating an
    expectation via nfqueue.

* tag 'nf-26-05-08' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
  netfilter: nft_ct: fix missing expect put in obj eval
  netfilter: nf_conntrack_sip: get helper before allocating expectation
  netfilter: ctnetlink: check tuple and mask in expectations created via nfqueue
  netfilter: nf_conntrack_expect: restore helper propagation via expectation
  netfilter: bridge: eb_tables: close module init race
  netfilter: x_tables: close dangling table module init race
  netfilter: ebtables: close dangling table module init race
  netfilter: ebtables: move to two-stage removal scheme
  netfilter: x_tables: add and use xtables_unregister_table_exit
  netfilter: x_tables: unregister the templates first
  netfilter: x_tables: add and use xt_unregister_table_pre_exit
  netfilter: x_tables: allocate hook ops while under mutex
  netfilter: x_tables: allow initial table replace without emitting audit log message
====================

Link: https://patch.msgid.link/20260507234509.603182-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-08 18:28:27 -07:00