From: Kees Cook <kees@kernel.org>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf@vger.kernel.org, Emil Tsalapatis <emil@etsalapatis.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Barret Rhoden <brho@google.com>,
Matt Bobrowski <mattbobrowski@google.com>,
kkd@meta.com, kernel-team@meta.com,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH bpf-next v5 08/12] bpf: Report rqspinlock deadlocks/timeout to BPF stderr
Date: Wed, 30 Jul 2025 16:02:12 -0700 [thread overview]
Message-ID: <202507301559.C832A9C@keescook> (raw)
In-Reply-To: <20250703204818.925464-9-memxor@gmail.com>
On Thu, Jul 03, 2025 at 01:48:14PM -0700, Kumar Kartikeya Dwivedi wrote:
> +static void bpf_prog_report_rqspinlock_violation(const char *str, void *lock, bool irqsave)
> +{
> + struct rqspinlock_held *rqh = this_cpu_ptr(&rqspinlock_held_locks);
> + struct bpf_stream_stage ss;
> + struct bpf_prog *prog;
> +
> + prog = bpf_prog_find_from_stack();
> + if (!prog)
> + return;
> + bpf_stream_stage(ss, prog, BPF_STDERR, ({
> + bpf_stream_printk(ss, "ERROR: %s for bpf_res_spin_lock%s\n", str, irqsave ? "_irqsave" : "");
> + bpf_stream_printk(ss, "Attempted lock = 0x%px\n", lock);
> + bpf_stream_printk(ss, "Total held locks = %d\n", rqh->cnt);
> + for (int i = 0; i < min(RES_NR_HELD, rqh->cnt); i++)
> + bpf_stream_printk(ss, "Held lock[%2d] = 0x%px\n", i, rqh->locks[i]);
> + bpf_stream_dump_stack(ss);
Please don't include %px in stuff going back to userspace in standard
error reporting. That's a kernel address leak:
https://docs.kernel.org/process/deprecated.html#p-format-specifier
I don't see any justification here, please remove the lock address or
use regular %p to get a hashed value.
--
Kees Cook
next prev parent reply other threads:[~2025-07-30 23:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-03 20:48 [PATCH bpf-next v5 00/12] BPF Standard Streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 01/12] bpf: Refactor bprintf buffer support Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 02/12] bpf: Introduce BPF standard streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 03/12] bpf: Add function to extract program source info Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 04/12] bpf: Ensure RCU lock is held around bpf_prog_ksym_find Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 05/12] bpf: Add function to find program from stack trace Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 06/12] bpf: Add dump_stack() analogue to print to BPF stderr Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 07/12] bpf: Report may_goto timeout " Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 08/12] bpf: Report rqspinlock deadlocks/timeout " Kumar Kartikeya Dwivedi
2025-07-30 23:02 ` Kees Cook [this message]
2025-07-30 23:07 ` Alexei Starovoitov
2025-07-30 23:09 ` Kees Cook
2025-07-30 23:13 ` Alexei Starovoitov
2025-07-30 23:19 ` Kees Cook
2025-07-03 20:48 ` [PATCH bpf-next v5 09/12] libbpf: Add bpf_stream_printk() macro Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 10/12] libbpf: Introduce bpf_prog_stream_read() API Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 11/12] bpftool: Add support for dumping streams Kumar Kartikeya Dwivedi
2025-07-03 20:48 ` [PATCH bpf-next v5 12/12] selftests/bpf: Add tests for prog streams Kumar Kartikeya Dwivedi
2025-07-04 2:40 ` [PATCH bpf-next v5 00/12] BPF Standard Streams patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202507301559.C832A9C@keescook \
--to=kees@kernel.org \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=brho@google.com \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=emil@etsalapatis.com \
--cc=kernel-team@meta.com \
--cc=kkd@meta.com \
--cc=linux-hardening@vger.kernel.org \
--cc=martin.lau@kernel.org \
--cc=mattbobrowski@google.com \
--cc=memxor@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox