Re: [PATCH bpf v3 1/2] bpf: Reject sleepable kprobe_multi programs at attach time

[Leon Hwang]

On 2/4/26 03:11, Varun R Mallya wrote:
> kprobe.multi programs run in atomic/RCU context and cannot sleep.
> However, bpf_kprobe_multi_link_attach() did not validate whether the
> program being attached had the sleepable flag set, allowing sleepable
> helpers such as bpf_copy_from_user() to be invoked from a non-sleepable
> context.
> 
> This causes a "sleeping function called from invalid context" splat:
> 
>   BUG: sleeping function called from invalid context at ./include/linux/uaccess.h:169
>   in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1787, name: sudo
>   preempt_count: 1, expected: 0
>   RCU nest depth: 2, expected: 0
> 
> Fix this by rejecting sleepable programs early in
> bpf_kprobe_multi_link_attach(), before any further processing.
> 
> Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
> Signed-off-by: Varun R Mallya <varunrmallya@xxxxxxxxx>

Acked-by: Leon Hwang <leon.hwang@xxxxxxxxx>

The cover letter is missing, and the change logs are missing, too.

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