linux-kernel - [PATCH] reject taskset for kernel threads

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Date:	Wed, 21 Mar 2007 21:53:53 +0100
From:	Olaf Hering <olaf@...fle.de>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] reject taskset for kernel threads


Do not allow taskset for kernel threads.
These commands will cause oopses due to stack corruption:

ls /proc/*/task | grep -v ^/ | xargs echo | xargs -n1 taskset -pc 2-9
taskset -pc 1 $$
taskset -pc 0 $((pidof john))

Possible fix in userland:

for i in ` ls /proc/*/task | grep -v ^/ `
do
	e=/proc/*/task/$i/exe
	if test -e $e
	then
		taskset -pc 2-9	$i
	fi
done


Signed-off-by: Olaf Hering <olaf@...fle.de>

---
 kernel/sched.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6.20/kernel/sched.c
===================================================================
--- linux-2.6.20.orig/kernel/sched.c
+++ linux-2.6.20/kernel/sched.c
@@ -4310,6 +4310,8 @@ long sched_setaffinity(pid_t pid, cpumas
 	read_unlock(&tasklist_lock);
 
 	retval = -EPERM;
+	if (!p->mm)
+		goto out_unlock;
 	if ((current->euid != p->euid) && (current->euid != p->uid) &&
 			!capable(CAP_SYS_NICE))
 		goto out_unlock;
-
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