Masami,
Do you want to take this? -- Steve On Sun, 04 May 2025 20:27:51 +0200 Paul Cacheux via B4 Relay <devnull+paulcacheux.gmail....@kernel.org> wrote: > Hello, > > As reported in [1] a race exists in the shared trace probe log > used to build error messages. This can cause kernel crashes > when building the actual error message, but the race happens > even for non-error tracefs uses, it's just not visible. > > Reproducer first reported that is still crashing: > > # 'p4' is invalid command which make kernel run into trace_probe_log_err() > cd /sys/kernel/debug/tracing > while true; do > echo 'p4:myprobe1 do_sys_openat2 dfd=%ax filename=%dx flags=%cx > mode=+4($stack)' >> kprobe_events & > echo 'p4:myprobe2 do_sys_openat2' >> kprobe_events & > echo 'p4:myprobe3 do_sys_openat2 dfd=%ax filename=%dx' >> kprobe_events & > done; > > The original email suggested to use a mutex or to allocate the > trace_probe_log on the stack. This patch implements a simpler > solution suggest during the review of the v1 where we only protect > access to the shared trace_probe_log with a mutex. This will prevent > any crash from happening. > > [1] > https://lore.kernel.org/all/20221121081103.3070449-1-zhengyeji...@huawei.com/T/ > > Signed-off-by: Paul Cacheux <paulcach...@gmail.com> > --- > Changes in v3: > - add some comment around the new mutex definition > - Link to v2: > https://lore.kernel.org/r/20250502-fix-trace-probe-log-race-v2-0-511ecc152...@gmail.com > > Changes in v2: > - change approach, and use the mutex based solution suggested during > review > - Link to v1: > https://lore.kernel.org/r/20250422-fix-trace-probe-log-race-v1-1-d2728d42c...@gmail.com > > --- > Paul Cacheux (2): > tracing: add missing trace_probe_log_clear for eprobes > tracing: protect trace_probe_log with mutex > > kernel/trace/trace_eprobe.c | 3 +++ > kernel/trace/trace_probe.c | 13 +++++++++++++ > 2 files changed, 16 insertions(+) > --- > base-commit: 95d3481af6dc90fd7175a7643fd108cdcb808ce5 > change-id: 20250420-fix-trace-probe-log-race-cc89d8e5fb15 > > Best regards,
