* [PATCH] signal: Initialize the info in ksignal
@ 2022-11-28 6:56 haifeng.xu
2022-12-01 23:40 ` Kees Cook
2022-12-01 23:42 ` Kees Cook
0 siblings, 2 replies; 3+ messages in thread
From: haifeng.xu @ 2022-11-28 6:56 UTC (permalink / raw)
To: brauner
Cc: ebiederm, oleg, keescook, tglx, peterz, elver, linux-kernel, haifeng.xu
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.
Signed-off-by: haifeng.xu <haifeng.xu@shopee.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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] signal: Initialize the info in ksignal
2022-11-28 6:56 [PATCH] signal: Initialize the info in ksignal haifeng.xu
@ 2022-12-01 23:40 ` Kees Cook
2022-12-01 23:42 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2022-12-01 23:40 UTC (permalink / raw)
To: haifeng.xu; +Cc: brauner, ebiederm, oleg, tglx, peterz, elver, linux-kernel
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@shopee.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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] signal: Initialize the info in ksignal
2022-11-28 6:56 [PATCH] signal: Initialize the info in ksignal haifeng.xu
2022-12-01 23:40 ` Kees Cook
@ 2022-12-01 23:42 ` Kees Cook
1 sibling, 0 replies; 3+ messages in thread
From: Kees Cook @ 2022-12-01 23:42 UTC (permalink / raw)
To: haifeng.xu, brauner
Cc: Kees Cook, elver, oleg, ebiederm, linux-kernel, tglx, peterz
On Mon, 28 Nov 2022 06:56:06 +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.
>
>
> [...]
Applied to for-next/hardening, thanks!
[1/1] signal: Initialize the info in ksignal
https://git.kernel.org/kees/c/935d428bb528
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-12-01 23:40 ` Kees Cook
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