From: Andrew Morton <akpm@linux-foundation.org>
To: Bradley Morgan <include@grrlz.net>
Cc: Feng Tang <feng.tang@linux.alibaba.com>,
Petr Mladek <pmladek@suse.com>,
Jinchao Wang <wangjinchao600@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] panic: fix va_list reuse in panic_try_force_cpu()
Date: Sun, 5 Jul 2026 12:10:14 -0700 [thread overview]
Message-ID: <20260705121014.d783e021f38f262faf2404f2@linux-foundation.org> (raw)
In-Reply-To: <20260705164123.18746-1-include@grrlz.net>
On Sun, 5 Jul 2026 16:41:23 +0000 Bradley Morgan <include@grrlz.net> wrote:
> vsnprintf() consumes the caller's va_list. When the redirect fails,
> vpanic() reuses it for the panic message, which is undefined
> behavior. Use va_copy().
Thanks.
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -412,7 +412,12 @@ static bool panic_try_force_cpu(const char *fmt, va_list args)
> * fall back to static message for early boot panics or allocation failure.
> */
> if (panic_force_buf) {
> - vsnprintf(panic_force_buf, PANIC_MSG_BUFSZ, fmt, args);
> + va_list ap;
> +
> + /* Do not consume args, the caller reuses it if we fail */
Nice comment!
> + va_copy(ap, args);
> + vsnprintf(panic_force_buf, PANIC_MSG_BUFSZ, fmt, ap);
> + va_end(ap);
> msg = panic_force_buf;
> } else {
> msg = "Redirected panic (buffer unavailable)";
AI review found a possible pre-existing thing in there (as usual,
sigh). Seems pretty improbable:
https://sashiko.dev/#/patchset/20260705164123.18746-1-include@grrlz.net
prev parent reply other threads:[~2026-07-05 19:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-05 16:41 [PATCH] panic: fix va_list reuse in panic_try_force_cpu() Bradley Morgan
2026-07-05 19:10 ` Andrew Morton [this message]
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