sysrq: Fix possible race with exiting task
sysrq should grab the tasklist lock, otherwise calling force_sig() is
not safe, as it might race with exiting task, which ->sighand might be
set to NULL already.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 7867b7c..a1bcad7 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -322,11 +322,13 @@
{
struct task_struct *p;
+ read_lock(&tasklist_lock);
for_each_process(p) {
if (p->mm && !is_global_init(p))
/* Not swapper, init nor kernel thread */
force_sig(sig, p);
}
+ read_unlock(&tasklist_lock);
}
static void sysrq_handle_term(int key)