Re: [PATCH bpf v5 2/3] bpf: Skip detached progs in trampoline images that are still in use

[sashiko-bot@kernel.org]

> bpf_tramp_image_put() makes sure a trampoline image is not freed while
> a task may still be running in it, but nothing similar is done for the
> progs called by that image. Detach drops the last prog reference right
> away and the prog is freed after grace periods, on the basis that a
> task still in the traced function skips the fexit progs once the nop at
> ip_after_call is patched to a jump.
> 
> That leaves out a task sleeping in a sleepable prog that runs before
> the detached one, which no grace period waits for:
> 
>   CPU 0                               CPU 1
>   in image I, sleeping in prog S
>                                       detach P from I's trampoline
>                                        -> new image, bpf_tramp_image_put(I)
>                                       bpf_prog_put(P), last ref
> [ ... ]
> Reported-by: Sechang Lim <rhkrqnwk98@gmail.com>
> Closes: https://lore.kernel.org/bpf/20260815071927.147049-1-zirajs7@gmail.com/
> Suggested-by: Alexei Starovoitov <ast@kernel.org>
> Assisted-by: Claude:unspecified
> Signed-off-by: Florent Revest (Anthropic) <florent.revest@linux.dev>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260926135605.1217928-1-florent.revest@linux.dev?part=2