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prev_padding represents the unused space of certain subbuffer. If the content of a call of relay_write() exceeds the limit of the remainder of this subbuffer, it will skip storing in the rest space and record the start point as buf->prev_padding in relay_switch_subbuf(). Since the buf is a per-cpu big buffer, the point of prev_padding as a global value for the whole buffer instead of a single subbuffer (whose padding info is stored in buf->padding[]) seems meaningless from the real use cases, so we don't bother to record it any more. Reviewed-by: Yushan Zhou <[email protected]> Signed-off-by: Jason Xing <[email protected]>
When using relay mechanism, we often encounter the case where new data are lost or old unconsumed data are overwritten because of slow reader. Add 'full' field in per-cpu buffer structure to detect if the above case is happening. Relay has two modes: 1) non-overwrite mode, 2) overwrite mode. So buffer being full here respectively means: 1) relayfs doesn't intend to accept new data and then simply drop them, or 2) relayfs is going to start over again and overwrite old unread data with new data. Note: this counter doesn't need any explicit lock to protect from being modified by different threads for the better performance consideration. Writers calling __relay_write/relay_write should consider how to use the lock and ensure it performs under the lock protection, thus it's not necessary to add a new small lock here. Reviewed-by: Yushan Zhou <[email protected]> Reviewed-by: Jens Axboe <[email protected]> Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Jason Xing <[email protected]>
In this version, only support getting the counter for buffer full and implement the framework of how it works. Users can pass certain flag to fetch what field/statistics they expect to know. Each time it only returns one result. So do not pass multiple flags. Reviewed-by: Yushan Zhou <[email protected]> Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Jason Xing <[email protected]>
Replace internal subbuf_start in blktrace with the default policy in relayfs. Remove dropped field from struct blktrace. Correspondingly, call the common helper in relay. By incrementing full_count to keep track of how many times we encountered a full buffer issue, user space will know how many events were lost. Reviewed-by: Yushan Zhou <[email protected]> Reviewed-by: Jens Axboe <[email protected]> Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Jason Xing <[email protected]>
It really doesn't matter if the user/admin knows what the last too big value is. Record how many times this case is triggered would be helpful. Solve the existing issue where relay_reset() doesn't restore the value. Store the counter in the per-cpu buffer structure instead of the global buffer structure. It also solves the racy condition which is likely to happen when a few of per-cpu buffers encounter the too big data case and then access the global field last_toobig without lock protection. Remove the printk in relay_close() since kernel module can directly call relay_stats() as they want. Reviewed-by: Yushan Zhou <[email protected]> Reviewed-by: Masami Hiramatsu (Google) <[email protected]> Signed-off-by: Jason Xing <[email protected]>
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In probe appletb_kbd_probe() a "struct appletb_kbd *kbd" is allocated via devm_kzalloc() to store touch bar keyboard related data. Later on if backlight_device_get_by_name() finds a backlight device with name "appletb_backlight" a timer (kbd->inactivity_timer) is setup with appletb_inactivity_timer() and the timer is armed to run after appletb_tb_dim_timeout (60) seconds. A use-after-free is triggered when failure occurs after the timer is armed. This ultimately means probe failure occurs and as a result the "struct appletb_kbd *kbd" which is device managed memory is freed. After 60 seconds the timer will have expired and __run_timers will attempt to access the timer (kbd->inactivity_timer) however the kdb structure has been freed causing a use-after free. [ 71.636938] ================================================================== [ 71.637915] BUG: KASAN: slab-use-after-free in __run_timers+0x7ad/0x890 [ 71.637915] Write of size 8 at addr ffff8881178c5958 by task swapper/1/0 [ 71.637915] [ 71.637915] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.16.0-rc2-00318-g739a6c93cc75-dirty #12 PREEMPT(voluntary) [ 71.637915] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 71.637915] Call Trace: [ 71.637915] <IRQ> [ 71.637915] dump_stack_lvl+0x53/0x70 [ 71.637915] print_report+0xce/0x670 [ 71.637915] ? __run_timers+0x7ad/0x890 [ 71.637915] kasan_report+0xce/0x100 [ 71.637915] ? __run_timers+0x7ad/0x890 [ 71.637915] __run_timers+0x7ad/0x890 [ 71.637915] ? __pfx___run_timers+0x10/0x10 [ 71.637915] ? update_process_times+0xfc/0x190 [ 71.637915] ? __pfx_update_process_times+0x10/0x10 [ 71.637915] ? _raw_spin_lock_irq+0x80/0xe0 [ 71.637915] ? _raw_spin_lock_irq+0x80/0xe0 [ 71.637915] ? __pfx__raw_spin_lock_irq+0x10/0x10 [ 71.637915] run_timer_softirq+0x141/0x240 [ 71.637915] ? __pfx_run_timer_softirq+0x10/0x10 [ 71.637915] ? __pfx___hrtimer_run_queues+0x10/0x10 [ 71.637915] ? kvm_clock_get_cycles+0x18/0x30 [ 71.637915] ? ktime_get+0x60/0x140 [ 71.637915] handle_softirqs+0x1b8/0x5c0 [ 71.637915] ? __pfx_handle_softirqs+0x10/0x10 [ 71.637915] irq_exit_rcu+0xaf/0xe0 [ 71.637915] sysvec_apic_timer_interrupt+0x6c/0x80 [ 71.637915] </IRQ> [ 71.637915] [ 71.637915] Allocated by task 39: [ 71.637915] kasan_save_stack+0x33/0x60 [ 71.637915] kasan_save_track+0x14/0x30 [ 71.637915] __kasan_kmalloc+0x8f/0xa0 [ 71.637915] __kmalloc_node_track_caller_noprof+0x195/0x420 [ 71.637915] devm_kmalloc+0x74/0x1e0 [ 71.637915] appletb_kbd_probe+0x37/0x3c0 [ 71.637915] hid_device_probe+0x2d1/0x680 [ 71.637915] really_probe+0x1c3/0x690 [ 71.637915] __driver_probe_device+0x247/0x300 [ 71.637915] driver_probe_device+0x49/0x210 [...] [ 71.637915] [ 71.637915] Freed by task 39: [ 71.637915] kasan_save_stack+0x33/0x60 [ 71.637915] kasan_save_track+0x14/0x30 [ 71.637915] kasan_save_free_info+0x3b/0x60 [ 71.637915] __kasan_slab_free+0x37/0x50 [ 71.637915] kfree+0xcf/0x360 [ 71.637915] devres_release_group+0x1f8/0x3c0 [ 71.637915] hid_device_probe+0x315/0x680 [ 71.637915] really_probe+0x1c3/0x690 [ 71.637915] __driver_probe_device+0x247/0x300 [ 71.637915] driver_probe_device+0x49/0x210 [...] The root cause of the issue is that the timer is not disarmed on failure paths leading to it remaining active and accessing freed memory. To fix this call timer_delete_sync() to deactivate the timer. Another small issue is that timer_delete_sync is called unconditionally in appletb_kbd_remove(), fix this by checking for a valid kbd->backlight_dev before calling timer_delete_sync. Fixes: 93a0fc4 ("HID: hid-appletb-kbd: add support for automatic brightness control while using the touchbar") Cc: [email protected] Signed-off-by: Qasim Ijaz <[email protected]> Reviewed-by: Aditya Garg <[email protected]> Signed-off-by: Jiri Kosina <[email protected]>
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Without the change `perf `hangs up on charaster devices. On my system
it's enough to run system-wide sampler for a few seconds to get the
hangup:
$ perf record -a -g --call-graph=dwarf
$ perf report
# hung
`strace` shows that hangup happens on reading on a character device
`/dev/dri/renderD128`
$ strace -y -f -p 2780484
strace: Process 2780484 attached
pread64(101</dev/dri/renderD128>, strace: Process 2780484 detached
It's call trace descends into `elfutils`:
$ gdb -p 2780484
(gdb) bt
#0 0x00007f5e508f04b7 in __libc_pread64 (fd=101, buf=0x7fff9df7edb0, count=0, offset=0)
at ../sysdeps/unix/sysv/linux/pread64.c:25
#1 0x00007f5e52b79515 in read_file () from /<<NIX>>/elfutils-0.192/lib/libelf.so.1
#2 0x00007f5e52b25666 in libdw_open_elf () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#3 0x00007f5e52b25907 in __libdw_open_file () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#4 0x00007f5e52b120a9 in dwfl_report_elf@@ELFUTILS_0.156 ()
from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#5 0x000000000068bf20 in __report_module (al=al@entry=0x7fff9df80010, ip=ip@entry=139803237033216, ui=ui@entry=0x5369b5e0)
at util/dso.h:537
#6 0x000000000068c3d1 in report_module (ip=139803237033216, ui=0x5369b5e0) at util/unwind-libdw.c:114
#7 frame_callback (state=0x535aef10, arg=0x5369b5e0) at util/unwind-libdw.c:242
#8 0x00007f5e52b261d3 in dwfl_thread_getframes () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#9 0x00007f5e52b25bdb in get_one_thread_cb () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#10 0x00007f5e52b25faa in dwfl_getthreads () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#11 0x00007f5e52b26514 in dwfl_getthread_frames () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
#12 0x000000000068c6ce in unwind__get_entries (cb=cb@entry=0x5d4620 <unwind_entry>, arg=arg@entry=0x10cd5fa0,
thread=thread@entry=0x1076a290, data=data@entry=0x7fff9df80540, max_stack=max_stack@entry=127,
best_effort=best_effort@entry=false) at util/thread.h:152
#13 0x00000000005dae95 in thread__resolve_callchain_unwind (evsel=0x106006d0, thread=0x1076a290, cursor=0x10cd5fa0,
sample=0x7fff9df80540, max_stack=127, symbols=true) at util/machine.c:2939
#14 thread__resolve_callchain_unwind (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, sample=0x7fff9df80540,
max_stack=127, symbols=true) at util/machine.c:2920
#15 __thread__resolve_callchain (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, evsel@entry=0x7fff9df80440,
sample=0x7fff9df80540, parent=parent@entry=0x7fff9df804a0, root_al=root_al@entry=0x7fff9df80440, max_stack=127, symbols=true)
at util/machine.c:2970
#16 0x00000000005d0cb2 in thread__resolve_callchain (thread=<optimized out>, cursor=<optimized out>, evsel=0x7fff9df80440,
sample=<optimized out>, parent=0x7fff9df804a0, root_al=0x7fff9df80440, max_stack=127) at util/machine.h:198
#17 sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fff9df804a0,
evsel=evsel@entry=0x106006d0, al=al@entry=0x7fff9df80440, max_stack=max_stack@entry=127) at util/callchain.c:1127
#18 0x0000000000617e08 in hist_entry_iter__add (iter=iter@entry=0x7fff9df80480, al=al@entry=0x7fff9df80440, max_stack_depth=127,
arg=arg@entry=0x7fff9df81ae0) at util/hist.c:1255
#19 0x000000000045d2d0 in process_sample_event (tool=0x7fff9df81ae0, event=<optimized out>, sample=0x7fff9df80540,
evsel=0x106006d0, machine=<optimized out>) at builtin-report.c:334
#20 0x00000000005e3bb1 in perf_session__deliver_event (session=0x105ff2c0, event=0x7f5c7d735ca0, tool=0x7fff9df81ae0,
file_offset=2914716832, file_path=0x105ffbf0 "perf.data") at util/session.c:1367
#21 0x00000000005e8d93 in do_flush (oe=0x105ffa50, show_progress=false) at util/ordered-events.c:245
#22 __ordered_events__flush (oe=0x105ffa50, how=OE_FLUSH__ROUND, timestamp=<optimized out>) at util/ordered-events.c:324
#23 0x00000000005e1f64 in perf_session__process_user_event (session=0x105ff2c0, event=0x7f5c7d752b18, file_offset=2914835224,
file_path=0x105ffbf0 "perf.data") at util/session.c:1419
#24 0x00000000005e47c7 in reader__read_event (rd=rd@entry=0x7fff9df81260, session=session@entry=0x105ff2c0,
--Type <RET> for more, q to quit, c to continue without paging--
quit
prog=prog@entry=0x7fff9df81220) at util/session.c:2132
#25 0x00000000005e4b37 in reader__process_events (rd=0x7fff9df81260, session=0x105ff2c0, prog=0x7fff9df81220)
at util/session.c:2181
#26 __perf_session__process_events (session=0x105ff2c0) at util/session.c:2226
#27 perf_session__process_events (session=session@entry=0x105ff2c0) at util/session.c:2390
#28 0x0000000000460add in __cmd_report (rep=0x7fff9df81ae0) at builtin-report.c:1076
#29 cmd_report (argc=<optimized out>, argv=<optimized out>) at builtin-report.c:1827
#30 0x00000000004c5a40 in run_builtin (p=p@entry=0xd8f7f8 <commands+312>, argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0)
at perf.c:351
#31 0x00000000004c5d63 in handle_internal_command (argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0) at perf.c:404
#32 0x0000000000442de3 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:448
#33 main (argc=<optimized out>, argv=0x7fff9df844b0) at perf.c:556
The hangup happens because nothing in` perf` or `elfutils` checks if a
mapped file is easily readable.
The change conservatively skips all non-regular files.
Signed-off-by: Sergei Trofimovich <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
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Symbolize stack traces by creating a live machine. Add this
functionality to dump_stack and switch dump_stack users to use
it. Switch TUI to use it. Add stack traces to the child test function
which can be useful to diagnose blocked code.
Example output:
```
$ perf test -vv PERF_RECORD_
...
7: PERF_RECORD_* events & perf_sample fields:
7: PERF_RECORD_* events & perf_sample fields : Running (1 active)
^C
Signal (2) while running tests.
Terminating tests with the same signal
Internal test harness failure. Completing any started tests:
: 7: PERF_RECORD_* events & perf_sample fields:
---- unexpected signal (2) ----
#0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
#1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
#2 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
#3 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
#4 0x7fc12fef1393 in __nanosleep nanosleep.c:26
#5 0x7fc12ff02d68 in __sleep sleep.c:55
#6 0x55788c63196b in test__PERF_RECORD perf-record.c:0
#7 0x55788c620fb0 in run_test_child builtin-test.c:0
#8 0x55788c5bd18d in start_command run-command.c:127
#9 0x55788c621ef3 in __cmd_test builtin-test.c:0
#10 0x55788c6225bf in cmd_test ??:0
#11 0x55788c5afbd0 in run_builtin perf.c:0
#12 0x55788c5afeeb in handle_internal_command perf.c:0
#13 0x55788c52b383 in main ??:0
#14 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
#15 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#16 0x55788c52b9d1 in _start ??:0
---- unexpected signal (2) ----
#0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
#1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
#2 0x7fc12fea3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45
#3 0x7fc12fe49fd9 in __GI___sigprocmask sigprocmask.c:26
#4 0x7fc12ff2601b in __longjmp_chk longjmp.c:36
#5 0x55788c6210c0 in print_test_result.isra.0 builtin-test.c:0
#6 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
#7 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
#8 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
#9 0x7fc12fef1393 in __nanosleep nanosleep.c:26
#10 0x7fc12ff02d68 in __sleep sleep.c:55
#11 0x55788c63196b in test__PERF_RECORD perf-record.c:0
#12 0x55788c620fb0 in run_test_child builtin-test.c:0
#13 0x55788c5bd18d in start_command run-command.c:127
#14 0x55788c621ef3 in __cmd_test builtin-test.c:0
#15 0x55788c6225bf in cmd_test ??:0
#16 0x55788c5afbd0 in run_builtin perf.c:0
#17 0x55788c5afeeb in handle_internal_command perf.c:0
#18 0x55788c52b383 in main ??:0
#19 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
#20 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#21 0x55788c52b9d1 in _start ??:0
7: PERF_RECORD_* events & perf_sample fields : Skip (permissions)
```
Signed-off-by: Ian Rogers <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
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Calling perf top with branch filters enabled on Intel CPU's
with branch counters logging (A.K.A LBR event logging [1]) support
results in a segfault.
$ perf top -e '{cpu_core/cpu-cycles/,cpu_core/event=0xc6,umask=0x3,frontend=0x11,name=frontend_retired_dsb_miss/}' -j any,counter
...
Thread 27 "perf" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffafff76c0 (LWP 949003)]
perf_env__find_br_cntr_info (env=0xf66dc0 <perf_env>, nr=0x0, width=0x7fffafff62c0) at util/env.c:653
653 *width = env->cpu_pmu_caps ? env->br_cntr_width :
(gdb) bt
#0 perf_env__find_br_cntr_info (env=0xf66dc0 <perf_env>, nr=0x0, width=0x7fffafff62c0) at util/env.c:653
#1 0x00000000005b1599 in symbol__account_br_cntr (branch=0x7fffcc3db580, evsel=0xfea2d0, offset=12, br_cntr=8) at util/annotate.c:345
#2 0x00000000005b17fb in symbol__account_cycles (addr=5658172, start=5658160, sym=0x7fffcc0ee420, cycles=539, evsel=0xfea2d0, br_cntr=8) at util/annotate.c:389
#3 0x00000000005b1976 in addr_map_symbol__account_cycles (ams=0x7fffcd7b01d0, start=0x7fffcd7b02b0, cycles=539, evsel=0xfea2d0, br_cntr=8) at util/annotate.c:422
#4 0x000000000068d57f in hist__account_cycles (bs=0x110d288, al=0x7fffafff6540, sample=0x7fffafff6760, nonany_branch_mode=false, total_cycles=0x0, evsel=0xfea2d0) at util/hist.c:2850
#5 0x0000000000446216 in hist_iter__top_callback (iter=0x7fffafff6590, al=0x7fffafff6540, single=true, arg=0x7fffffff9e00) at builtin-top.c:737
#6 0x0000000000689787 in hist_entry_iter__add (iter=0x7fffafff6590, al=0x7fffafff6540, max_stack_depth=127, arg=0x7fffffff9e00) at util/hist.c:1359
#7 0x0000000000446710 in perf_event__process_sample (tool=0x7fffffff9e00, event=0x110d250, evsel=0xfea2d0, sample=0x7fffafff6760, machine=0x108c968) at builtin-top.c:845
#8 0x0000000000447735 in deliver_event (qe=0x7fffffffa120, qevent=0x10fc200) at builtin-top.c:1211
#9 0x000000000064ccae in do_flush (oe=0x7fffffffa120, show_progress=false) at util/ordered-events.c:245
#10 0x000000000064d005 in __ordered_events__flush (oe=0x7fffffffa120, how=OE_FLUSH__TOP, timestamp=0) at util/ordered-events.c:324
#11 0x000000000064d0ef in ordered_events__flush (oe=0x7fffffffa120, how=OE_FLUSH__TOP) at util/ordered-events.c:342
#12 0x00000000004472a9 in process_thread (arg=0x7fffffff9e00) at builtin-top.c:1120
#13 0x00007ffff6e7dba8 in start_thread (arg=<optimized out>) at pthread_create.c:448
#14 0x00007ffff6f01b8c in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78
The cause is that perf_env__find_br_cntr_info tries to access a
null pointer pmu_caps in the perf_env struct. A similar issue exists
for homogeneous core systems which use the cpu_pmu_caps structure.
Fix this by populating cpu_pmu_caps and pmu_caps structures with
values from sysfs when calling perf top with branch stack sampling
enabled.
[1], LBR event logging introduced here:
https://lore.kernel.org/all/[email protected]/
Reviewed-by: Ian Rogers <[email protected]>
Signed-off-by: Thomas Falcon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Namhyung Kim <[email protected]>
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Aug 23, 2025
Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 #12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR frame with incomplete TAG, via AF_PACKET socket on 'veth0_to_hsr'. The first HSR-layer function to process this frame is hsr_handle_frame(). It and then checks if the protocol is ETH_P_PRP or ETH_P_HSR. If it is, it calls skb_set_network_header(skb, ETH_HLEN + HSR_HLEN), without checking that the skb is long enough. For the crashing frame it is not, and hence the skb->network_header and skb->mac_len fields are set incorrectly, pointing after the end of the linear buffer. I will call this a BUG#1 and it is what is addressed by this patch. In the crashing scenario before the fix, the skb continues to go down the hsr path as follows. hsr_handle_frame() then calls this sequence hsr_forward_skb() fill_frame_info() hsr->proto_ops->fill_frame_info() hsr_fill_frame_info() hsr_fill_frame_info() contains a check that intends to check whether the skb actually contains the HSR header. But the check relies on the skb->mac_len field which was erroneously setup due to BUG#1, so the check passes and the execution continues back in the hsr_forward_skb(): hsr_forward_skb() hsr_forward_do() hsr->proto_ops->get_untagged_frame() hsr_get_untagged_frame() create_stripped_skb_hsr() In create_stripped_skb_hsr(), a copy of the skb is created and is further corrupted by operation that attempts to strip the HSR tag in a call to __pskb_copy(). The skb enters create_stripped_skb_hsr() with ethernet header pushed in linear buffer. The skb_pull(skb_in, HSR_HLEN) thus pulls 6 bytes of ethernet header into the headroom, creating skb_in with a headroom of size 8. The subsequent __pskb_copy() then creates an skb with headroom of just 2 and skb->len of just 12, this is how it looks after the copy: gdb) p skb->len $10 = 12 (gdb) p skb->data $11 = (unsigned char *) 0xffff888041e45382 "\252\252\252\252\252!\210\373", (gdb) p skb->head $12 = (unsigned char *) 0xffff888041e45380 "" It seems create_stripped_skb_hsr() assumes that ETH header is pulled in the headroom when it's entered, because it just pulls HSR header on top. But that is not the case in our code-path and we end up with the corrupted skb instead. I will call this BUG#2 *I got confused here because it seems that under no conditions can create_stripped_skb_hsr() work well, the assumption it makes is not true during the processing of hsr frames - since the skb_push() in hsr_handle_frame to skb_pull in hsr_deliver_master(). I wonder whether I missed something here.* Next, the execution arrives in hsr_deliver_master(). It calls skb_pull(ETH_HLEN), which just returns NULL - the SKB does not have enough space for the pull (as it only has 12 bytes in total at this point). *The skb_pull() here further suggests that ethernet header is meant to be pushed through the whole hsr processing and create_stripped_skb_hsr() should pull it before doing the HSR header pull.* hsr_deliver_master() then puts the corrupted skb on the queue, it is then picked up from there by bridge frame handling layer and finally lands in br_dev_queue_push_xmit where it panics. Cc: [email protected] Fixes: 48b491a ("net: hsr: fix mac_len checks") Reported-by: [email protected] Signed-off-by: Jakub Acs <[email protected]> Reviewed-by: Eric Dumazet <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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Oct 9, 2025
The test starts a workload and then opens events. If the events fail
to open, for example because of perf_event_paranoid, the gopipe of the
workload is leaked and the file descriptor leak check fails when the
test exits. To avoid this cancel the workload when opening the events
fails.
Before:
```
$ perf test -vv 7
7: PERF_RECORD_* events & perf_sample fields:
--- start ---
test child forked, pid 1189568
Using CPUID GenuineIntel-6-B7-1
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
config 0xa00000000 (cpu_atom/PERF_COUNT_HW_CPU_CYCLES/)
disabled 1
------------------------------------------------------------
sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8
sys_perf_event_open failed, error -13
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
config 0xa00000000 (cpu_atom/PERF_COUNT_HW_CPU_CYCLES/)
disabled 1
exclude_kernel 1
------------------------------------------------------------
sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8 = 3
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
config 0x400000000 (cpu_core/PERF_COUNT_HW_CPU_CYCLES/)
disabled 1
------------------------------------------------------------
sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8
sys_perf_event_open failed, error -13
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
config 0x400000000 (cpu_core/PERF_COUNT_HW_CPU_CYCLES/)
disabled 1
exclude_kernel 1
------------------------------------------------------------
sys_perf_event_open: pid 0 cpu -1 group_fd -1 flags 0x8 = 3
Attempt to add: software/cpu-clock/
..after resolving event: software/config=0/
cpu-clock -> software/cpu-clock/
------------------------------------------------------------
perf_event_attr:
type 1 (PERF_TYPE_SOFTWARE)
size 136
config 0x9 (PERF_COUNT_SW_DUMMY)
sample_type IP|TID|TIME|CPU
read_format ID|LOST
disabled 1
inherit 1
mmap 1
comm 1
enable_on_exec 1
task 1
sample_id_all 1
mmap2 1
comm_exec 1
ksymbol 1
bpf_event 1
{ wakeup_events, wakeup_watermark } 1
------------------------------------------------------------
sys_perf_event_open: pid 1189569 cpu 0 group_fd -1 flags 0x8
sys_perf_event_open failed, error -13
perf_evlist__open: Permission denied
---- end(-2) ----
Leak of file descriptor 6 that opened: 'pipe:[14200347]'
---- unexpected signal (6) ----
iFailed to read build ID for //anon
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#0 0x565358f6666e in child_test_sig_handler builtin-test.c:311
#1 0x7f29ce849df0 in __restore_rt libc_sigaction.c:0
#2 0x7f29ce89e95c in __pthread_kill_implementation pthread_kill.c:44
#3 0x7f29ce849cc2 in raise raise.c:27
#4 0x7f29ce8324ac in abort abort.c:81
#5 0x565358f662d4 in check_leaks builtin-test.c:226
#6 0x565358f6682e in run_test_child builtin-test.c:344
#7 0x565358ef7121 in start_command run-command.c:128
#8 0x565358f67273 in start_test builtin-test.c:545
#9 0x565358f6771d in __cmd_test builtin-test.c:647
#10 0x565358f682bd in cmd_test builtin-test.c:849
#11 0x565358ee5ded in run_builtin perf.c:349
#12 0x565358ee6085 in handle_internal_command perf.c:401
#13 0x565358ee61de in run_argv perf.c:448
#14 0x565358ee6527 in main perf.c:555
#15 0x7f29ce833ca8 in __libc_start_call_main libc_start_call_main.h:74
#16 0x7f29ce833d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#17 0x565358e391c1 in _start perf[851c1]
7: PERF_RECORD_* events & perf_sample fields : FAILED!
```
After:
```
$ perf test 7
7: PERF_RECORD_* events & perf_sample fields : Skip (permissions)
```
Fixes: 16d00fe ("perf tests: Move test__PERF_RECORD into separate object")
Signed-off-by: Ian Rogers <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Athira Rajeev <[email protected]>
Cc: Chun-Tse Shao <[email protected]>
Cc: Howard Chu <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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that referenced
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Feb 13, 2026
Check all loaded modules and report any that have their 'taint'
flags set. The tainted module output format is:
* <module_name> (<taint_flags>)
Example output:
Kernel is "tainted" for the following reasons:
* externally-built ('out-of-tree') module was loaded (#12)
* unsigned module was loaded (#13)
Raw taint value as int/string: 12288/'G OE '
Tainted modules:
* dump_test (OE)
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Randy Dunlap <[email protected]>
Acked-by: Thorsten Leemhuis <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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that referenced
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Feb 22, 2026
The ETM decoder incorrectly assumed that auxtrace queue indices were
equivalent to CPU number. This assumption is used for inserting records
into the queue, and for fetching queues when given a CPU number. This
assumption held when Perf always opened a dummy event on every CPU, even
if the user provided a subset of CPUs on the commandline, resulting in
the indices aligning.
For example:
# event : name = cs_etm//u, , id = { 2451, 2452 }, type = 11 (cs_etm), size = 136, config = 0x4010, { sample_period, samp>
# event : name = dummy:u, , id = { 2453, 2454, 2455, 2456 }, type = 1 (PERF_TYPE_SOFTWARE), size = 136, config = 0x9 (PER>
0 0 0x200 [0xd0]: PERF_RECORD_ID_INDEX nr: 6
... id: 2451 idx: 2 cpu: 2 tid: -1
... id: 2452 idx: 3 cpu: 3 tid: -1
... id: 2453 idx: 0 cpu: 0 tid: -1
... id: 2454 idx: 1 cpu: 1 tid: -1
... id: 2455 idx: 2 cpu: 2 tid: -1
... id: 2456 idx: 3 cpu: 3 tid: -1
Since commit 811082e ("perf parse-events: Support user CPUs mixed
with threads/processes") the dummy event no longer behaves in this way,
making the ETM event indices start from 0 on the first CPU recorded
regardless of its ID:
# event : name = cs_etm//u, , id = { 771, 772 }, type = 11 (cs_etm), size = 144, config = 0x4010, { sample_period, sample>
# event : name = dummy:u, , id = { 773, 774 }, type = 1 (PERF_TYPE_SOFTWARE), size = 144, config = 0x9 (PERF_COUNT_SW_DUM>
0 0 0x200 [0x90]: PERF_RECORD_ID_INDEX nr: 4
... id: 771 idx: 0 cpu: 2 tid: -1
... id: 772 idx: 1 cpu: 3 tid: -1
... id: 773 idx: 0 cpu: 2 tid: -1
... id: 774 idx: 1 cpu: 3 tid: -1
This causes the following segfault when decoding:
$ perf record -e cs_etm//u -C 2,3 -- true
$ perf report
perf: Segmentation fault
-------- backtrace --------
#0 0xaaaabf9fd020 in ui__signal_backtrace setup.c:110
#1 0xffffab5c7930 in __kernel_rt_sigreturn [vdso][930]
#2 0xaaaabfb68d30 in cs_etm_decoder__reset cs-etm-decoder.c:85
#3 0xaaaabfb65930 in cs_etm__get_data_block cs-etm.c:2032
#4 0xaaaabfb666fc in cs_etm__run_per_cpu_timeless_decoder cs-etm.c:2551
#5 0xaaaabfb6692c in (cs_etm__process_timeless_queues cs-etm.c:2612
#6 0xaaaabfb63390 in cs_etm__flush_events cs-etm.c:921
#7 0xaaaabfb324c0 in auxtrace__flush_events auxtrace.c:2915
#8 0xaaaabfaac378 in __perf_session__process_events session.c:2285
#9 0xaaaabfaacc9c in perf_session__process_events session.c:2442
#10 0xaaaabf8d3d90 in __cmd_report builtin-report.c:1085
#11 0xaaaabf8d6944 in cmd_report builtin-report.c:1866
#12 0xaaaabf95ebfc in run_builtin perf.c:351
#13 0xaaaabf95eeb0 in handle_internal_command perf.c:404
#14 0xaaaabf95f068 in run_argv perf.c:451
#15 0xaaaabf95f390 in main perf.c:558
#16 0xffffaab97400 in __libc_start_call_main libc_start_call_main.h:74
#17 0xffffaab974d8 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
#18 0xaaaabf8aa8f0 in _start perf[7a8f0]
Fix it by inserting into the queues based on CPU number, rather than
using the index.
Fixes: 811082e ("perf parse-events: Support user CPUs mixed with threads/processes")
Signed-off-by: James Clark <[email protected]>
Tested-by: Leo Yan <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: [email protected]
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Garry <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suzuki Poulouse <[email protected]>
Cc: Thomas Falcon <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
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that referenced
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Mar 13, 2026
XDP multi-buf programs can modify the layout of the XDP buffer when the program calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The referenced commit in the fixes tag corrected the assumption in the mlx5 driver that the XDP buffer layout doesn't change during a program execution. However, this fix introduced another issue: the dropped fragments still need to be counted on the driver side to avoid page fragment reference counting issues. Such issue can be observed with the test_xdp_native_adjst_tail_shrnk_data selftest when using a payload of 3600 and shrinking by 256 bytes (an upcoming selftest patch): the last fragment gets released by the XDP code but doesn't get tracked by the driver. This results in a negative pp_ref_count during page release and the following splat: WARNING: include/net/page_pool/helpers.h:297 at mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core], CPU#12: ip/3137 Modules linked in: [...] CPU: 12 UID: 0 PID: 3137 Comm: ip Not tainted 6.19.0-rc3+ #12 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core] [...] Call Trace: <TASK> mlx5e_dealloc_rx_wqe+0xcb/0x1a0 [mlx5_core] mlx5e_free_rx_descs+0x7f/0x110 [mlx5_core] mlx5e_close_rq+0x50/0x60 [mlx5_core] mlx5e_close_queues+0x36/0x2c0 [mlx5_core] mlx5e_close_channel+0x1c/0x50 [mlx5_core] mlx5e_close_channels+0x45/0x80 [mlx5_core] mlx5e_safe_switch_params+0x1a5/0x230 [mlx5_core] mlx5e_change_mtu+0xf3/0x2f0 [mlx5_core] netif_set_mtu_ext+0xf1/0x230 do_setlink.isra.0+0x219/0x1180 rtnl_newlink+0x79f/0xb60 rtnetlink_rcv_msg+0x213/0x3a0 netlink_rcv_skb+0x48/0xf0 netlink_unicast+0x24a/0x350 netlink_sendmsg+0x1ee/0x410 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x232/0x280 ___sys_sendmsg+0x78/0xb0 __sys_sendmsg+0x5f/0xb0 [...] do_syscall_64+0x57/0xc50 This patch fixes the issue by doing page frag counting on all the original XDP buffer fragments for all relevant XDP actions (XDP_TX , XDP_REDIRECT and XDP_PASS). This is basically reverting to the original counting before the commit in the fixes tag. As frag_page is still pointing to the original tail, the nr_frags parameter to xdp_update_skb_frags_info() needs to be calculated in a different way to reflect the new nr_frags. Fixes: afd5ba5 ("net/mlx5e: RX, Fix generating skb from non-linear xdp_buff for legacy RQ") Signed-off-by: Dragos Tatulea <[email protected]> Signed-off-by: Tariq Toukan <[email protected]> Reviewed-by: Amery Hung <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
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Pull request for series with
subject: relayfs: misc changes
version: 4
url: https://patchwork.kernel.org/project/linux-block/list/?series=970068