The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
5bf2fedca8f5 ("exec: Copy oldsighand->action under spin-lock")
021691559245 ("exec: Factor unshare_sighand out of de_thread and call it separately")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 5bf2fedca8f59379025b0d52f917b9ddb9bfe17e Mon Sep 17 00:00:00 2001
From: Bernd Edlinger <bernd.edlinger@xxxxxxxxxx>
Date: Mon, 7 Jun 2021 15:54:27 +0200
Subject: [PATCH] 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@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/AM8PR10MB470871DEBD1DED081F9CC391E4389@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
diff --git a/fs/exec.c b/fs/exec.c
index 349a5da91efe..32dc8cf5fceb 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);
