Pull tracing fix from Steven Rostedt:
"Fix synthetic event "strcat" overrun
New synthetic event code used strcat() and miscalculated the ending,
causing the concatenation to write beyond the allocated memory.
Instead of using strncat(), the code is switched over to seq_buf which
has all the mechanisms in place to protect against writing more than
what is allocated, and cleans up the code a bit"
* tag 'trace-v5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing, synthetic events: Replace buggy strcat() with seq_buf operations
There was a memory corruption bug happening while running the synthetic
event selftests:
kmemleak: Cannot insert 0xffff8c196fa2afe5 into the object search tree (overlaps existing)
CPU: 5 PID: 6866 Comm: ftracetest Tainted: G W 5.9.0-rc5-test+ #577
Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v03.03 07/14/2016
Call Trace:
dump_stack+0x8d/0xc0
create_object.cold+0x3b/0x60
slab_post_alloc_hook+0x57/0x510
? tracing_map_init+0x178/0x340
__kmalloc+0x1b1/0x390
tracing_map_init+0x178/0x340
event_hist_trigger_func+0x523/0xa40
trigger_process_regex+0xc5/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xca/0x210
ksys_write+0x70/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fef0a63a487
Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
RSP: 002b:00007fff76f18398 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000039 RCX: 00007fef0a63a487
RDX: 0000000000000039 RSI: 000055eb3b26d690 RDI: 0000000000000001
RBP: 000055eb3b26d690 R08: 000000000000000a R09: 0000000000000038
R10: 000055eb3b2cdb80 R11: 0000000000000246 R12: 0000000000000039
R13: 00007fef0a70b500 R14: 0000000000000039 R15: 00007fef0a70b700
kmemleak: Kernel memory leak detector disabled
kmemleak: Object 0xffff8c196fa2afe0 (size 8):
kmemleak: comm "ftracetest", pid 6866, jiffies 4295082531
kmemleak: min_count = 1
kmemleak: count = 0
kmemleak: flags = 0x1
kmemleak: checksum = 0
kmemleak: backtrace:
__kmalloc+0x1b1/0x390
tracing_map_init+0x1be/0x340
event_hist_trigger_func+0x523/0xa40
trigger_process_regex+0xc5/0x110
event_trigger_write+0x71/0xd0
vfs_write+0xca/0x210
ksys_write+0x70/0xf0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The cause came down to a use of strcat() that was adding an string that was
shorten, but the strcat() did not take that into account.
strcat() is extremely dangerous as it does not care how big the buffer is.
Replace it with seq_buf operations that prevent the buffer from being
overwritten if what is being written is bigger than the buffer.
Fixes: 10819e2579 ("tracing: Handle synthetic event array field type checking correctly")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
tid_addr is not a "pointer to (pointer to int in userspace)"; it is in
fact a "pointer to (pointer to int in userspace) in userspace". So
sparse rightfully complains about passing a kernel pointer to
put_user().
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull timer fixes from Thomas Gleixner:
"A time namespace fix and a matching selftest. The futex absolute
timeouts which are based on CLOCK_MONOTONIC require time namespace
corrected. This was missed in the original time namesapce support"
* tag 'timers-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
selftests/timens: Add a test for futex()
futex: Adjust absolute futex timeouts with per time namespace offset
Pull scheduler fixes from Thomas Gleixner:
"Two scheduler fixes:
- A trivial build fix for sched_feat() to compile correctly with
CONFIG_JUMP_LABEL=n
- Replace a zero lenght array with a flexible array"
* tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/features: Fix !CONFIG_JUMP_LABEL case
sched: Replace zero-length array with flexible-array
Pull SafeSetID updates from Micah Morton:
"The changes are mostly contained to within the SafeSetID LSM, with the
exception of a few 1-line changes to change some ns_capable() calls to
ns_capable_setid() -- causing a flag (CAP_OPT_INSETID) to be set that
is examined by SafeSetID code and nothing else in the kernel.
The changes to SafeSetID internally allow for setting up GID
transition security policies, as already existed for UIDs"
* tag 'safesetid-5.10' of git://github.com/micah-morton/linux:
LSM: SafeSetID: Fix warnings reported by test bot
LSM: SafeSetID: Add GID security policy handling
LSM: Signal to SafeSetID when setting group IDs
Pull random32 updates from Willy Tarreau:
"Make prandom_u32() less predictable.
This is the cleanup of the latest series of prandom_u32
experimentations consisting in using SipHash instead of Tausworthe to
produce the randoms used by the network stack.
The changes to the files were kept minimal, and the controversial
commit that used to take noise from the fast_pool (f227e3ec3b) was
reverted. Instead, a dedicated "net_rand_noise" per_cpu variable is
fed from various sources of activities (networking, scheduling) to
perturb the SipHash state using fast, non-trivially predictable data,
instead of keeping it fully deterministic. The goal is essentially to
make any occasional memory leakage or brute-force attempt useless.
The resulting code was verified to be very slightly faster on x86_64
than what is was with the controversial commit above, though this
remains barely above measurement noise. It was also tested on i386 and
arm, and build- tested only on arm64"
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
* tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom:
random32: add a selftest for the prandom32 code
random32: add noise from network and scheduling activity
random32: make prandom_u32() output unpredictable
Pull dma-mapping fixes from Christoph Hellwig:
- document the new dma_{alloc,free}_pages() API
- two fixups for the dma-mapping.h split
* tag 'dma-mapping-5.10-1' of git://git.infradead.org/users/hch/dma-mapping:
dma-mapping: document dma_{alloc,free}_pages
dma-mapping: move more functions to dma-map-ops.h
ARM/sa1111: add a missing include of dma-map-ops.h
With the removal of the interrupt perturbations in previous random32
change (random32: make prandom_u32() output unpredictable), the PRNG
has become 100% deterministic again. While SipHash is expected to be
way more robust against brute force than the previous Tausworthe LFSR,
there's still the risk that whoever has even one temporary access to
the PRNG's internal state is able to predict all subsequent draws till
the next reseed (roughly every minute). This may happen through a side
channel attack or any data leak.
This patch restores the spirit of commit f227e3ec3b ("random32: update
the net random state on interrupt and activity") in that it will perturb
the internal PRNG's statee using externally collected noise, except that
it will not pick that noise from the random pool's bits nor upon
interrupt, but will rather combine a few elements along the Tx path
that are collectively hard to predict, such as dev, skb and txq
pointers, packet length and jiffies values. These ones are combined
using a single round of SipHash into a single long variable that is
mixed with the net_rand_state upon each invocation.
The operation was inlined because it produces very small and efficient
code, typically 3 xor, 2 add and 2 rol. The performance was measured
to be the same (even very slightly better) than before the switch to
SipHash; on a 6-core 12-thread Core i7-8700k equipped with a 40G NIC
(i40e), the connection rate dropped from 556k/s to 555k/s while the
SYN cookie rate grew from 5.38 Mpps to 5.45 Mpps.
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
Cc: George Spelvin <lkml@sdf.org>
Cc: Amit Klein <aksecurity@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tytso@mit.edu
Cc: Florian Westphal <fw@strlen.de>
Cc: Marc Plumb <lkml.mplumb@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Non-cryptographic PRNGs may have great statistical properties, but
are usually trivially predictable to someone who knows the algorithm,
given a small sample of their output. An LFSR like prandom_u32() is
particularly simple, even if the sample is widely scattered bits.
It turns out the network stack uses prandom_u32() for some things like
random port numbers which it would prefer are *not* trivially predictable.
Predictability led to a practical DNS spoofing attack. Oops.
This patch replaces the LFSR with a homebrew cryptographic PRNG based
on the SipHash round function, which is in turn seeded with 128 bits
of strong random key. (The authors of SipHash have *not* been consulted
about this abuse of their algorithm.) Speed is prioritized over security;
attacks are rare, while performance is always wanted.
Replacing all callers of prandom_u32() is the quick fix.
Whether to reinstate a weaker PRNG for uses which can tolerate it
is an open question.
Commit f227e3ec3b ("random32: update the net random state on interrupt
and activity") was an earlier attempt at a solution. This patch replaces
it.
Reported-by: Amit Klein <aksecurity@gmail.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Eric Dumazet <edumazet@google.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: tytso@mit.edu
Cc: Florian Westphal <fw@strlen.de>
Cc: Marc Plumb <lkml.mplumb@gmail.com>
Fixes: f227e3ec3b ("random32: update the net random state on interrupt and activity")
Signed-off-by: George Spelvin <lkml@sdf.org>
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
[ willy: partial reversal of f227e3ec3b5c; moved SIPROUND definitions
to prandom.h for later use; merged George's prandom_seed() proposal;
inlined siprand_u32(); replaced the net_rand_state[] array with 4
members to fix a build issue; cosmetic cleanups to make checkpatch
happy; fixed RANDOM32_SELFTEST build ]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Pull tracing ring-buffer fix from Steven Rostedt:
"The success return value of ring_buffer_resize() is stated to be
zero and checked that way.
But it was incorrectly returning the size allocated.
Also, a fix to a comment"
* tag 'trace-v5.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ring-buffer: Update the description for ring_buffer_wait
ring-buffer: Return 0 on success from ring_buffer_resize()
Pull more power management updates from Rafael Wysocki:
"First of all, the adaptive voltage scaling (AVS) drivers go to new
platform-specific locations as planned (this part was reported to have
merge conflicts against the new arm-soc updates in linux-next).
In addition to that, there are some fixes (intel_idle, intel_pstate,
RAPL, acpi_cpufreq), the addition of on/off notifiers and idle state
accounting support to the generic power domains (genpd) code and some
janitorial changes all over.
Specifics:
- Move the AVS drivers to new platform-specific locations and get rid
of the drivers/power/avs directory (Ulf Hansson).
- Add on/off notifiers and idle state accounting support to the
generic power domains (genpd) framework (Ulf Hansson, Lina Iyer).
- Ulf will maintain the PM domain part of cpuidle-psci (Ulf Hansson).
- Make intel_idle disregard ACPI _CST if it cannot use the data
returned by that method (Mel Gorman).
- Modify intel_pstate to avoid leaving useless sysfs directory
structure behind if it cannot be registered (Chen Yu).
- Fix domain detection in the RAPL power capping driver and prevent
it from failing to enumerate the Psys RAPL domain (Zhang Rui).
- Allow acpi-cpufreq to use ACPI _PSD information with Family 19 and
later AMD chips (Wei Huang).
- Update the driver assumptions comment in intel_idle and fix a
kerneldoc comment in the runtime PM framework (Alexander Monakov,
Bean Huo).
- Avoid unnecessary resets of the cached frequency in the schedutil
cpufreq governor to reduce overhead (Wei Wang).
- Clean up the cpufreq core a bit (Viresh Kumar).
- Make assorted minor janitorial changes (Daniel Lezcano, Geert
Uytterhoeven, Hubert Jasudowicz, Tom Rix).
- Clean up and optimize the cpupower utility somewhat (Colin Ian
King, Martin Kaistra)"
* tag 'pm-5.10-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (23 commits)
PM: sleep: remove unreachable break
PM: AVS: Drop the avs directory and the corresponding Kconfig
PM: AVS: qcom-cpr: Move the driver to the qcom specific drivers
PM: runtime: Fix typo in pm_runtime_set_active() helper comment
PM: domains: Fix build error for genpd notifiers
powercap: Fix typo in Kconfig "Plance" -> "Plane"
cpufreq: schedutil: restore cached freq when next_f is not changed
acpi-cpufreq: Honor _PSD table setting on new AMD CPUs
PM: AVS: smartreflex Move driver to soc specific drivers
PM: AVS: rockchip-io: Move the driver to the rockchip specific drivers
PM: domains: enable domain idle state accounting
PM: domains: Add curly braces to delimit comment + statement block
PM: domains: Add support for PM domain on/off notifiers for genpd
powercap/intel_rapl: enumerate Psys RAPL domain together with package RAPL domain
powercap/intel_rapl: Fix domain detection
intel_idle: Ignore _CST if control cannot be taken from the platform
cpuidle: Remove pointless stub
intel_idle: mention assumption that WBINVD is not needed
MAINTAINERS: Add section for cpuidle-psci PM domain
cpufreq: intel_pstate: Delete intel_pstate sysfs if failed to register the driver
...
Pull networking fixes from Jakub Kicinski:
"Cross-tree/merge window issues:
- rtl8150: don't incorrectly assign random MAC addresses; fix late in
the 5.9 cycle started depending on a return code from a function
which changed with the 5.10 PR from the usb subsystem
Current release regressions:
- Revert "virtio-net: ethtool configurable RXCSUM", it was causing
crashes at probe when control vq was not negotiated/available
Previous release regressions:
- ixgbe: fix probing of multi-port 10 Gigabit Intel NICs with an MDIO
bus, only first device would be probed correctly
- nexthop: Fix performance regression in nexthop deletion by
effectively switching from recently added synchronize_rcu() to
synchronize_rcu_expedited()
- netsec: ignore 'phy-mode' device property on ACPI systems; the
property is not populated correctly by the firmware, but firmware
configures the PHY so just keep boot settings
Previous releases - always broken:
- tcp: fix to update snd_wl1 in bulk receiver fast path, addressing
bulk transfers getting "stuck"
- icmp: randomize the global rate limiter to prevent attackers from
getting useful signal
- r8169: fix operation under forced interrupt threading, make the
driver always use hard irqs, even on RT, given the handler is light
and only wants to schedule napi (and do so through a _irqoff()
variant, preferably)
- bpf: Enforce pointer id generation for all may-be-null register
type to avoid pointers erroneously getting marked as null-checked
- tipc: re-configure queue limit for broadcast link
- net/sched: act_tunnel_key: fix OOB write in case of IPv6 ERSPAN
tunnels
- fix various issues in chelsio inline tls driver
Misc:
- bpf: improve just-added bpf_redirect_neigh() helper api to support
supplying nexthop by the caller - in case BPF program has already
done a lookup we can avoid doing another one
- remove unnecessary break statements
- make MCTCP not select IPV6, but rather depend on it"
* tag 'net-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (62 commits)
tcp: fix to update snd_wl1 in bulk receiver fast path
net: Properly typecast int values to set sk_max_pacing_rate
netfilter: nf_fwd_netdev: clear timestamp in forwarding path
ibmvnic: save changed mac address to adapter->mac_addr
selftests: mptcp: depends on built-in IPv6
Revert "virtio-net: ethtool configurable RXCSUM"
rtnetlink: fix data overflow in rtnl_calcit()
net: ethernet: mtk-star-emac: select REGMAP_MMIO
net: hdlc_raw_eth: Clear the IFF_TX_SKB_SHARING flag after calling ether_setup
net: hdlc: In hdlc_rcv, check to make sure dev is an HDLC device
bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static
bpf, selftests: Extend test_tc_redirect to use modified bpf_redirect_neigh()
bpf: Fix bpf_redirect_neigh helper api to support supplying nexthop
mptcp: depends on IPV6 but not as a module
sfc: move initialisation of efx->filter_sem to efx_init_struct()
mpls: load mpls_gso after mpls_iptunnel
net/sched: act_tunnel_key: fix OOB write in case of IPv6 ERSPAN tunnels
net/sched: act_gate: Unlock ->tcfa_lock in tc_setup_flow_action()
net: dsa: bcm_sf2: make const array static, makes object smaller
mptcp: MPTCP_IPV6 should depend on IPV6 instead of selecting it
...
Pull arch task_work cleanups from Jens Axboe:
"Two cleanups that don't fit other categories:
- Finally get the task_work_add() cleanup done properly, so we don't
have random 0/1/false/true/TWA_SIGNAL confusing use cases. Updates
all callers, and also fixes up the documentation for
task_work_add().
- While working on some TIF related changes for 5.11, this
TIF_NOTIFY_RESUME cleanup fell out of that. Remove some arch
duplication for how that is handled"
* tag 'arch-cleanup-2020-10-22' of git://git.kernel.dk/linux-block:
task_work: cleanup notification modes
tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume()
Pull Kbuild updates from Masahiro Yamada:
- Support 'make compile_commands.json' to generate the compilation
database more easily, avoiding stale entries
- Support 'make clang-analyzer' and 'make clang-tidy' for static checks
using clang-tidy
- Preprocess scripts/modules.lds.S to allow CONFIG options in the
module linker script
- Drop cc-option tests from compiler flags supported by our minimal
GCC/Clang versions
- Use always 12-digits commit hash for CONFIG_LOCALVERSION_AUTO=y
- Use sha1 build id for both BFD linker and LLD
- Improve deb-pkg for reproducible builds and rootless builds
- Remove stale, useless scripts/namespace.pl
- Turn -Wreturn-type warning into error
- Fix build error of deb-pkg when CONFIG_MODULES=n
- Replace 'hostname' command with more portable 'uname -n'
- Various Makefile cleanups
* tag 'kbuild-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
kbuild: Use uname for LINUX_COMPILE_HOST detection
kbuild: Only add -fno-var-tracking-assignments for old GCC versions
kbuild: remove leftover comment for filechk utility
treewide: remove DISABLE_LTO
kbuild: deb-pkg: clean up package name variables
kbuild: deb-pkg: do not build linux-headers package if CONFIG_MODULES=n
kbuild: enforce -Werror=return-type
scripts: remove namespace.pl
builddeb: Add support for all required debian/rules targets
builddeb: Enable rootless builds
builddeb: Pass -n to gzip for reproducible packages
kbuild: split the build log of kallsyms
kbuild: explicitly specify the build id style
scripts/setlocalversion: make git describe output more reliable
kbuild: remove cc-option test of -Werror=date-time
kbuild: remove cc-option test of -fno-stack-check
kbuild: remove cc-option test of -fno-strict-overflow
kbuild: move CFLAGS_{KASAN,UBSAN,KCSAN} exports to relevant Makefiles
kbuild: remove redundant CONFIG_KASAN check from scripts/Makefile.kasan
kbuild: do not create built-in objects for external module builds
...
Pull modules updates from Jessica Yu:
"Code cleanups: more informative error messages and statically
initialize init_free_wq to avoid a workqueue warning"
* tag 'modules-for-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: statically initialize init section freeing data
module: Add more error message for failed kernel module loading
Pull initial set_fs() removal from Al Viro:
"Christoph's set_fs base series + fixups"
* 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Allow a NULL pos pointer to __kernel_read
fs: Allow a NULL pos pointer to __kernel_write
powerpc: remove address space overrides using set_fs()
powerpc: use non-set_fs based maccess routines
x86: remove address space overrides using set_fs()
x86: make TASK_SIZE_MAX usable from assembly code
x86: move PAGE_OFFSET, TASK_SIZE & friends to page_{32,64}_types.h
lkdtm: remove set_fs-based tests
test_bitmap: remove user bitmap tests
uaccess: add infrastructure for kernel builds with set_fs()
fs: don't allow splice read/write without explicit ops
fs: don't allow kernel reads and writes without iter ops
sysctl: Convert to iter interfaces
proc: add a read_iter method to proc proc_ops
proc: cleanup the compat vs no compat file ops
proc: remove a level of indentation in proc_get_inode
We don't need to check the new buffer size, and the return value
had confused resize_buffer_duplicate_size().
...
ret = ring_buffer_resize(trace_buf->buffer,
per_cpu_ptr(size_buf->data,cpu_id)->entries, cpu_id);
if (ret == 0)
per_cpu_ptr(trace_buf->data, cpu_id)->entries =
per_cpu_ptr(size_buf->data, cpu_id)->entries;
...
Link: https://lkml.kernel.org/r/20201019142242.11560-1-hqjagain@gmail.com
Cc: stable@vger.kernel.org
Fixes: d60da506cb ("tracing: Add a resize function to make one buffer equivalent to another buffer")
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This change removes all instances of DISABLE_LTO from
Makefiles, as they are currently unused, and the preferred
method of disabling LTO is to filter out the flags instead.
Note added by Masahiro Yamada:
DISABLE_LTO was added as preparation for GCC LTO, but GCC LTO was
not pulled into the mainline. (https://lkml.org/lkml/2014/4/8/272)
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Due to a mismerge a bunch of prototypes that should have moved to
dma-map-ops.h are still in dma-mapping.h, fix that up.
Signed-off-by: Christoph Hellwig <hch@lst.de>
The commit af7ec13833 ("bpf: Add bpf_skc_to_tcp6_sock() helper")
introduces RET_PTR_TO_BTF_ID_OR_NULL and
the commit eaa6bcb71e ("bpf: Introduce bpf_per_cpu_ptr()")
introduces RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL.
Note that for RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL, the reg0->type
could become PTR_TO_MEM_OR_NULL which is not covered by
BPF_PROBE_MEM.
The BPF_REG_0 will then hold a _OR_NULL pointer type. This _OR_NULL
pointer type requires the bpf program to explicitly do a NULL check first.
After NULL check, the verifier will mark all registers having
the same reg->id as safe to use. However, the reg->id
is not set for those new _OR_NULL return types. One of the ways
that may be wrong is, checking NULL for one btf_id typed pointer will
end up validating all other btf_id typed pointers because
all of them have id == 0. The later tests will exercise
this path.
To fix it and also avoid similar issue in the future, this patch
moves the id generation logic out of each individual RET type
test in check_helper_call(). Instead, it does one
reg_type_may_be_null() test and then do the id generation
if needed.
This patch also adds a WARN_ON_ONCE in mark_ptr_or_null_reg()
to catch future breakage.
The _OR_NULL pointer usage in the bpf_iter_reg.ctx_arg_info is
fine because it just happens that the existing id generation after
check_ctx_access() has covered it. It is also using the
reg_type_may_be_null() to decide if id generation is needed or not.
Fixes: af7ec13833 ("bpf: Add bpf_skc_to_tcp6_sock() helper")
Fixes: eaa6bcb71e ("bpf: Introduce bpf_per_cpu_ptr()")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201019194212.1050855-1-kafai@fb.com
