From: Leon Hwang <leon.hwang@linux.dev>
To: Varun R Mallya <varunrmallya@gmail.com>, bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, memxor@gmail.com,
yonghong.song@linux.dev, jolsa@kernel.org, rostedt@goodmis.org,
mhiramat@kernel.org, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH bpf v3 1/2] bpf: Reject sleepable kprobe_multi programs at attach time
Date: Thu, 2 Apr 2026 12:13:08 +0800 [thread overview]
Message-ID: <f0342ed8-e390-4913-88c6-4c707017be00@linux.dev> (raw)
In-Reply-To: <20260401191126.440683-1-varunrmallya@gmail.com>
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@gmail.com>
Acked-by: Leon Hwang <leon.hwang@linux.dev>
The cover letter is missing, and the change logs are missing, too.
[...]
next prev parent reply other threads:[~2026-04-02 4:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-01 19:11 [PATCH bpf v3 1/2] bpf: Reject sleepable kprobe_multi programs at attach time Varun R Mallya
2026-04-01 19:11 ` [PATCH bpf v3 2/2] selftests/bpf: Add test to ensure kprobe_multi is not sleepable Varun R Mallya
2026-04-01 22:50 ` Kumar Kartikeya Dwivedi
2026-04-02 9:46 ` Jiri Olsa
2026-04-06 20:11 ` Kumar Kartikeya Dwivedi
2026-04-02 4:13 ` Leon Hwang
2026-04-01 22:45 ` [PATCH bpf v3 1/2] bpf: Reject sleepable kprobe_multi programs at attach time Kumar Kartikeya Dwivedi
2026-04-02 4:13 ` Leon Hwang [this message]
2026-04-02 9:47 ` Jiri Olsa
2026-04-02 16:50 ` patchwork-bot+netdevbpf
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