When vmci_transport_recv_connecting_server() returns an error,
vmci_transport_recv_listen() calls vsock_remove_pending() but never
calls sk_acceptq_removed(). This leaves sk_ack_backlog incremented
permanently.
Repeated handshake failures (malformed packets, queue pair alloc
failure, event subscribe failure) cause sk_ack_backlog to climb
toward sk_max_ack_backlog. Once it reaches the limit the listener
permanently refuses all new connections with -ECONNREFUSED, a
silent denial of service requiring a process restart to recover.
The two existing sk_acceptq_removed() calls in af_vsock.c do not
cover this path: line 764 checks vsock_is_pending() which returns
false after vsock_remove_pending(), and line 1889 is only reached
on successful accept().
Fix by balancing sk_acceptq_added() with sk_acceptq_removed() on
the error path.
Fixes: d021c34405 ("VSOCK: Introduce VM Sockets")
Cc: stable@vger.kernel.org
Signed-off-by: Raf Dickson <rafdog35@gmail.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260526104356.469928-1-rafdog35@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg
before entering the send loop, but virtio_transport_alloc_skb() still
fills the skb before it inherits that uarg. When fixed-buffer vectored
zerocopy hits MAX_SKB_FRAGS, io_sg_from_iter() may partially attach
managed frags and return -EMSGSIZE. The rollback path call kfree_skb()
to free an skb that carries SKBFL_MANAGED_FRAG_REFS but no uarg, so
skb_release_data() falls through to ordinary frag unref.
Pass the uarg into virtio_transport_alloc_skb() and bind it immediately
before virtio_transport_fill_skb(). This keeps control or no-payload skbs
untouched while ensuring success and rollback share one lifetime rule.
Fixes: 581512a6dc ("vsock/virtio: MSG_ZEROCOPY flag support")
Signed-off-by: Lin Ma <malin89@huawei.com>
Signed-off-by: Rongzhen Cui <cuirongzhen@huawei.com>
Signed-off-by: Jingguo Tan <tanjingguo@huawei.com>
Acked-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260527023301.1075581-1-malin89@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
vsock_poll() reads vsk->peer_shutdown before taking the socket lock
to set EPOLLHUP and EPOLLRDHUP, then reads it again after taking
the lock to report EOF readability. A shutdown packet can update
peer_shutdown while poll is waiting for the lock, so one poll invocation
can report EOF readability without the corresponding HUP/RDHUP bits.
For connectible sockets, take one peer_shutdown snapshot after
lock_sock() and use it for all peer-shutdown-derived poll bits. For
datagram sockets, which do not take lock_sock() in poll(), take one
lockless READ_ONCE() snapshot and pair it with WRITE_ONCE() on the
writer side.
This keeps the peer-shutdown-derived bits internally consistent for each
poll pass.
Fixes: d021c34405 ("VSOCK: Introduce VM Sockets")
Signed-off-by: Ziyu Zhang <ziyuzhang201@gmail.com>
Link: https://patch.msgid.link/20260519165636.62542-1-ziyuzhang201@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
After commit 059b7dbd20 ("vsock/virtio: fix potential unbounded skb
queue"), virtio_transport_inc_rx_pkt() subtracts per-skb overhead from
buf_alloc when checking whether a new packet fits. This reduces the
effective receive buffer below what the user configured via
SO_VM_SOCKETS_BUFFER_SIZE, causing legitimate data packets to be
silently dropped and applications that rely on the full buffer size
to deadlock.
Also, the reduced space is not communicated to the remote peer, so
its credit calculation accounts more credit than the receiver will
actually accept, causing data loss (there is no retransmission).
With this approach we currently have failures in
tools/testing/vsock/vsock_test.c. Test 18 sometimes fails, while
test 22 always fails in this way:
18 - SOCK_STREAM MSG_ZEROCOPY...hash mismatch
22 - SOCK_STREAM virtio credit update + SO_RCVLOWAT...send failed:
Resource temporarily unavailable
Fix by allowing at most `buf_alloc * 2` as the total budget for payload
plus skb overhead in virtio_transport_inc_rx_pkt(), similar to how
SO_RCVBUF is doubled to reserve space for sk_buff metadata.
This preserves the full buf_alloc for payload under normal operation,
while still bounding the skb queue growth.
With this patch, all tests in tools/testing/vsock/vsock_test.c are
now passing again.
Fixes: 059b7dbd20 ("vsock/virtio: fix potential unbounded skb queue")
Cc: stable@vger.kernel.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260518090656.134588-3-sgarzare@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When there is no more space to queue an incoming packet, the packet is
silently dropped. This causes data loss without any notification to
either peer, since there is no retransmission.
Under normal circumstances, this should never happen. However, it could
happen if the other peer doesn't respect the credit, or if the skb
overhead, which we recently began to take into account with commit
059b7dbd20 ("vsock/virtio: fix potential unbounded skb queue"),
is too high.
Fix this by resetting the connection and setting the local socket error
to ENOBUFS when virtio_transport_recv_enqueue() can no longer queue a
packet, so both peers are explicitly notified of the failure rather than
silently losing data.
Fixes: ae6fcfbf5f ("vsock/virtio: discard packets if credit is not respected")
Cc: stable@vger.kernel.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260518090656.134588-2-sgarzare@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
vmci_transport_recv_connecting_server() returned err = 0 for a peer
RST in its default switch arm:
err = pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST ? 0 : -EINVAL;
That made vmci_transport_recv_listen() skip vsock_remove_pending(),
leaving the pending socket on the listener's pending_links with
sk_state = TCP_CLOSE while destroy: still dropped the explicit
reference taken before schedule_delayed_work().
One second later vsock_pending_work() observed is_pending=true and
performed full cleanup: vsock_remove_pending() then the two trailing
sock_put(sk) calls -- the first reached refcount 0 and __sk_freed
the socket, and the second wrote into the freed object:
BUG: KASAN: slab-use-after-free in refcount_warn_saturate
Write of size 4 at addr ffff88800b1cac80 by task kworker
Workqueue: events vsock_pending_work
Treat peer RST like any other unexpected packet type (err = -EINVAL).
All destroy: arms now return err < 0, so vmci_transport_recv_listen()
removes pending from pending_links synchronously and
vsock_pending_work() takes the is_pending=false / !rejected branch,
dropping only its own work reference. This also closes the
multi-packet race Sashiko reported on v2: pending is removed from
the list before any subsequent packet can find it.
The pre-existing sk_acceptq_removed() gap on the err < 0 path of
vmci_transport_recv_listen() that Sashiko also noted is not
introduced or changed by this patch.
Tested on lts-6.12.79 with KASAN: 52/100 unpatched -> 0/100 patched.
Fixes: d021c34405 ("VSOCK: Introduce VM Sockets")
Cc: stable@vger.kernel.org
Signed-off-by: Minh Nguyen <minhnguyen.080505@gmail.com>
Acked-by: Bryan Tan <bryan-bt.tan@broadcom.com>
Link: https://patch.msgid.link/20260519102310.237181-1-minhnguyen.080505@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When a large message is fragmented into multiple skbs, the zerocopy
uarg is only allocated and attached to the last skb in the loop.
Non-final skbs carry pinned user pages with no completion tracking,
so the kernel has no way to notify userspace when those pages are safe
to reuse. If the loop breaks early the uarg is never allocated at all,
leaking pinned pages with no completion notification.
Fix this by following the approach used by TCP: allocate the zerocopy
uarg (if not provided by the caller) before the send loop and attach
it to every skb via skb_zcopy_set(), which takes a reference per skb.
Each skb's completion properly decrements the refcount, and the
notification only fires after the last skb is freed.
On failure, if no data was sent, the uarg is cleanly aborted via
net_zcopy_put_abort().
This issue was initially discovered by sashiko while reviewing commit
1cb36e2522 ("vsock/virtio: fix MSG_ZEROCOPY pinned-pages accounting")
but was pre-existing.
Fixes: 581512a6dc ("vsock/virtio: MSG_ZEROCOPY flag support")
Closes: https://sashiko.dev/#/patchset/20260420132051.217589-1-sgarzare%40redhat.com
Reported-by: Maher Azzouzi <maherazz04@gmail.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Link: https://patch.msgid.link/20260514092948.268720-1-sgarzare@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
For non-linear skbs, virtio_transport_build_skb() goes through
virtio_transport_copy_nonlinear_skb() to copy the original payload
in the new skb to be delivered to the vsockmon tap device.
This manually initializes an iov_iter but does not set iov_iter.count.
Since the iov_iter is zero-initialized, the copy length is zero and no
payload is actually copied to the monitor interface, leaving data
un-initialized.
Fix this by removing the linear vs non-linear split and using
skb_copy_datagram_iter() with iov_iter_kvec() for all cases, as
vhost-vsock already does. This handles both linear and non-linear skbs,
properly initializes the iov_iter, and removes the now unused
virtio_transport_copy_nonlinear_skb().
While touching this code, let's also check the return value of
skb_copy_datagram_iter(), even though it's unlikely to fail.
Fixes: 4b0bf10eb0 ("vsock/virtio: non-linear skb handling for tap")
Reported-by: Yiqi Sun <sunyiqixm@gmail.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Reviewed-by: Arseniy Krasnov <avkrasnov@rulkc.org>
Link: https://patch.msgid.link/20260508164411.261440-3-sgarzare@redhat.com
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
virtio_transport_build_skb() builds a new skb to be delivered to the
vsockmon tap device. To build the new skb, it uses the original skb
data length as payload length, but as the comment notes, the original
packet stored in the skb may have been split in multiple packets, so we
need to use the length in the header, which is correctly updated before
the packet is delivered to the tap, and the offset for the data.
This was also similar to what we did before commit 71dc9ec9ac
("virtio/vsock: replace virtio_vsock_pkt with sk_buff") where we probably
missed something during the skb conversion.
Also update the comment above, which was left stale by the skb
conversion and still mentioned a buffer pointer that no longer exists.
Fixes: 71dc9ec9ac ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Reviewed-by: Arseniy Krasnov <avkrasnov@rulkc.org>
Link: https://patch.msgid.link/20260508164411.261440-2-sgarzare@redhat.com
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
virtio_transport_init_zcopy_skb() uses iter->count as the size argument
for msg_zerocopy_realloc(), which in turn passes it to
mm_account_pinned_pages() for RLIMIT_MEMLOCK accounting. However, this
function is called after virtio_transport_fill_skb() has already consumed
the iterator via __zerocopy_sg_from_iter(), so on the last skb, iter->count
will be 0, skipping the RLIMIT_MEMLOCK enforcement.
Pass pkt_len (the total bytes being sent) as an explicit parameter to
virtio_transport_init_zcopy_skb() instead of reading the already-consumed
iter->count.
This matches TCP and UDP, which both call msg_zerocopy_realloc() with
the original message size.
Fixes: 581512a6dc ("vsock/virtio: MSG_ZEROCOPY flag support")
Reported-by: Yiming Qian <yimingqian591@gmail.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260420132051.217589-1-sgarzare@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Commit f0c5827d07 unluckily causes a regression for the FIN packet,
and the final read syscall gets an error rather than 0.
Ideally, we would want to fix hvs_channel_readable_payload() so that it
could return 0 in the FIN scenario, but it's not good for the hv_sock
driver to use the VMBus ringbuffer's cached priv_read_index, which is
internal data in the VMBus driver.
Fix the regression in hv_sock by returning 0 rather than -EIO.
Fixes: f0c5827d07 ("hv_sock: Return the readable bytes in hvs_stream_has_data()")
Cc: stable@vger.kernel.org
Reported-by: Ben Hillis <Ben.Hillis@microsoft.com>
Reported-by: Mitchell Levy <levymitchell0@gmail.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260416191433.840637-1-decui@microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
`virtio_transport_stream_do_peek()` does not account for the skb offset
when computing the number of bytes to copy.
This means that, after a partial recv() that advances the offset, a peek
requesting more bytes than are available in the sk_buff causes
`skb_copy_datagram_iter()` to go past the valid payload, resulting in
a -EFAULT.
The dequeue path already handles this correctly.
Apply the same logic to the peek path.
Fixes: 0df7cd3c13 ("vsock/virtio/vhost: read data from non-linear skb")
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
Signed-off-by: Luigi Leonardi <leonardi@redhat.com>
Link: https://patch.msgid.link/20260415-fix_peek-v4-1-8207e872759e@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
virtio_transport_recv_listen() calls sk_acceptq_added() before
vsock_assign_transport(). If vsock_assign_transport() fails or
selects a different transport, the error path returns without
calling sk_acceptq_removed(), permanently incrementing
sk_ack_backlog.
After approximately backlog+1 such failures, sk_acceptq_is_full()
returns true, causing the listener to reject all new connections.
Fix by moving sk_acceptq_added() to after the transport validation,
matching the pattern used by vmci_transport and hyperv_transport.
Fixes: c0cfa2d8a7 ("vsock: add multi-transports support")
Signed-off-by: Dudu Lu <phx0fer@gmail.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20260413131409.19022-1-phx0fer@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Merge in late fixes in preparation for the net-next PR.
Conflicts:
include/net/sch_generic.h
a6bd339dbb ("net_sched: fix skb memory leak in deferred qdisc drops")
ff2998f29f ("net: sched: introduce qdisc-specific drop reason tracing")
https://lore.kernel.org/adz0iX85FHMz0HdO@sirena.org.uk
drivers/net/ethernet/airoha/airoha_eth.c
1acdfbdb51 ("net: airoha: Fix VIP configuration for AN7583 SoC")
bf3471e6e6 ("net: airoha: Make flow control source port mapping dependent on nbq parameter")
Adjacent changes:
drivers/net/ethernet/airoha/airoha_ppe.c
f44218cd5e ("net: airoha: Reset PPE cpu port configuration in airoha_ppe_hw_init()")
7da62262ec ("inet: add ip_local_port_step_width sysctl to improve port usage distribution")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In vsock_update_buffer_size(), the buffer size was being clamped to the
maximum first, and then to the minimum. If a user sets a minimum buffer
size larger than the maximum, the minimum check overrides the maximum
check, inverting the constraint.
This breaks the intended socket memory boundaries by allowing the
vsk->buffer_size to grow beyond the configured vsk->buffer_max_size.
Fix this by checking the minimum first, and then the maximum. This
ensures the buffer size never exceeds the buffer_max_size.
Fixes: b9f2b0ffde ("vsock: handle buffer_size sockopts in the core")
Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Norbert Szetei <norbert@doyensec.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/180118C5-8BCF-4A63-A305-4EE53A34AB9C@doyensec.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
A common pattern in epoll network servers is to eagerly accept all
pending connections from the non-blocking listening socket after
epoll_wait indicates the socket is ready by calling accept in a loop
until EAGAIN is returned indicating that the backlog is empty.
Scheduling a timeout for a non-blocking accept with an empty backlog
meant AF_VSOCK sockets used by epoll network servers incurred hundreds
of microseconds of additional latency per accept loop compared to
AF_INET or AF_UNIX sockets.
Signed-off-by: Laurence Rowe <laurencerowe@gmail.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260402204918.130395-1-laurencerowe@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The `child_ns_mode_locked` field lives in `struct net`, which persists
across vsock module reloads. When the module is unloaded and reloaded,
`vsock_net_init()` resets `mode` and `child_ns_mode` back to their
default values, but does not reset `child_ns_mode_locked`.
The stale lock from the previous module load causes subsequent writes
to `child_ns_mode` to silently fail: `vsock_net_set_child_mode()` sees
the old lock, skips updating the actual value, and returns success
when the requested mode matches the stale lock. The sysctl handler
reports no error, but `child_ns_mode` remains unchanged.
Steps to reproduce:
$ modprobe vsock
$ echo local > /proc/sys/net/vsock/child_ns_mode
$ cat /proc/sys/net/vsock/child_ns_mode
local
$ modprobe -r vsock
$ modprobe vsock
$ echo local > /proc/sys/net/vsock/child_ns_mode
$ cat /proc/sys/net/vsock/child_ns_mode
global <--- expected "local"
Fix this by initializing `child_ns_mode_locked` to 0 (unlocked) in
`vsock_net_init()`, so the write-once mechanism works correctly after
module reload.
Fixes: 102eab95f0 ("vsock: lock down child_ns_mode as write-once")
Reported-by: Jin Liu <jinl@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260401092153.28462-1-sgarzare@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
When no H2G transport is loaded, vsock currently routes all CIDs to the
G2H transport (commit 65b422d9b6 ("vsock: forward all packets to the
host when no H2G is registered"). Extend that existing behavior: when
an H2G transport is loaded but does not claim a given CID, the
connection falls back to G2H in the same way.
This matters in environments like Nitro Enclaves, where an instance may
run nested VMs via vhost-vsock (H2G) while also needing to reach sibling
enclaves at higher CIDs through virtio-vsock-pci (G2H). With the old
code, any CID > 2 was unconditionally routed to H2G when vhost was
loaded, making those enclaves unreachable without setting
VMADDR_FLAG_TO_HOST explicitly on every connect.
Requiring every application to set VMADDR_FLAG_TO_HOST creates friction:
tools like socat, iperf, and others would all need to learn about it.
The flag was introduced 6 years ago and I am still not aware of any tool
that supports it. Even if there was support, it would be cumbersome to
use. The most natural experience is a single CID address space where H2G
only wins for CIDs it actually owns, and everything else falls through to
G2H, extending the behavior that already exists when H2G is absent.
To give user space at least a hint that the kernel applied this logic,
automatically set the VMADDR_FLAG_TO_HOST on the remote address so it
can determine the path taken via getpeername().
Add a per-network namespace sysctl net.vsock.g2h_fallback (default 1).
At 0 it forces strict routing: H2G always wins for CID > VMADDR_CID_HOST,
or ENODEV if H2G is not loaded.
Signed-off-by: Alexander Graf <graf@amazon.com>
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://patch.msgid.link/20260304230027.59857-1-graf@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
