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Message-ID: <202212011537.371DD6639@keescook>
Date: Thu, 1 Dec 2022 15:40:15 -0800
From: Kees Cook <keescook@...omium.org>
To: "haifeng.xu" <haifeng.xu@...pee.com>
Cc: brauner@...nel.org, ebiederm@...ssion.com, oleg@...hat.com,
tglx@...utronix.de, peterz@...radead.org, elver@...gle.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] signal: Initialize the info in ksignal
On Mon, Nov 28, 2022 at 06:56:06AM +0000, haifeng.xu wrote:
> When handing the SIGNAL_GROUP_EXIT flag, the info in ksignal isn't cleared.
> However, the info acquired by dequeue_synchronous_signal/dequeue_signal is
> initialized and can be safely used. Fortunately, the fatal signal process
> just uses the si_signo and doesn't use any other member. Even so, the
> initialization before use is more safer.
Yeah, this patch seems correct -- get_signal() is usually called with
an uninitialized stack variable, and normally goes through dequeue_*
helpers which do a copy. The fatal path doesn't.
-Kees
> Signed-off-by: haifeng.xu <haifeng.xu@...pee.com>
> ---
> kernel/signal.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index d140672185a4..b9b0c8c620e7 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -2693,6 +2693,7 @@ bool get_signal(struct ksignal *ksig)
> /* Has this task already been marked for death? */
> if ((signal->flags & SIGNAL_GROUP_EXIT) ||
> signal->group_exec_task) {
> + clear_siginfo(&ksig->info);
> ksig->info.si_signo = signr = SIGKILL;
> sigdelset(¤t->pending.signal, SIGKILL);
> trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO,
> --
> 2.25.1
>
--
Kees Cook
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