Re: [PATCH] perf/bpf: Fix data race in __perf_event_overflow

[bot+bpf-ci]

> commit ffa161d3558e4937793a0c3e98e19e4b22e58bd9
> Author: Deepanshu Kartikey <kartikey406@xxxxxxxxx>
> Date:   Wed Aug 12 05:23:31 2026 +0530
>
>     perf/bpf: Fix data race in __perf_event_overflow
>
>     perf_event_detach_bpf_prog() writes event->prog = NULL
>     under bpf_event_mutex, while __perf_event_overflow() reads
>     event->prog concurrently without any lock protection. This
>     causes a data race detected by KCSAN.
>
>     __perf_event_overflow() can be called from interrupt/NMI
>     context, so it cannot acquire bpf_event_mutex. Fix the race
>     by using WRITE_ONCE() in perf_event_detach_bpf_prog() and
>     READ_ONCE() in __perf_event_overflow(). Also store the result
>     of READ_ONCE() in a local variable to avoid reading event->prog
>     twice which could result in a NULL pointer dereference if the
>     pointer becomes NULL between the two reads.
>
>     Reported-by: syzbot+651d2774bd1d8395595f@xxxxxxxxxxxxxxxxxxxxxxxxx
>     Closes: https://syzkaller.appspot.com/bug?extid=651d2774bd1d8395595f
>     Fixes: f11f10bfa1ca ("perf/bpf: Call BPF handler directly, not through overflow machinery")
>     Signed-off-by: Deepanshu Kartikey <kartikey406@xxxxxxxxx>
>     Reported-by: syzbot+651d2774bd1d8395595f@xxxxxxxxxxxxxxxxxxxxxxxxx
>     Signed-off-by: Deepanshu Kartikey <kartikey406@xxxxxxxxx>

The trailer block contains duplicate tags: both Reported-by: and
Signed-off-by: appear twice. Also, the second Reported-by: is placed
after the first Signed-off-by:, which breaks the conventional trailer
ordering (Reported-by/Closes/Fixes should come before Signed-off-by).

Should the duplicates be collapsed to one of each, in proper trailer order?


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