From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 7 Jun 2021 13:54:27 +0000 (+0200)
Subject: exec: Copy oldsighand->action under spin-lock
X-Git-Tag: v6.6.17~6048^2~13
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5bf2fedca8f59379025b0d52f917b9ddb9bfe17e;p=platform%2Fkernel%2Flinux-rpi.git

exec: Copy oldsighand->action under spin-lock

unshare_sighand should only access oldsighand->action
while holding oldsighand->siglock, to make sure that
newsighand->action is in a consistent state.

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/AM8PR10MB470871DEBD1DED081F9CC391E4389@AM8PR10MB4708.EURPRD10.PROD.OUTLOOK.COM
---

diff --git a/fs/exec.c b/fs/exec.c
index 349a5da..32dc8cf 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1197,11 +1197,11 @@ static int unshare_sighand(struct task_struct *me)
 			return -ENOMEM;
 
 		refcount_set(&newsighand->count, 1);
-		memcpy(newsighand->action, oldsighand->action,
-		       sizeof(newsighand->action));
 
 		write_lock_irq(&tasklist_lock);
 		spin_lock(&oldsighand->siglock);
+		memcpy(newsighand->action, oldsighand->action,
+		       sizeof(newsighand->action));
 		rcu_assign_pointer(me->sighand, newsighand);
 		spin_unlock(&oldsighand->siglock);
 		write_unlock_irq(&tasklist_lock);