klist: del waiter from klist_remove_waiters before wakeup waitting process

There is a race between klist_remove and klist_release. klist_remove uses a local var waiter saved on stack. When klist_release calls wake_up_process(waiter->process) to wake up the waiter, waiter might run immediately and reuse the stack. Then, klist_release calls list_del(&waiter->list) to change previous wait data and cause prior waiter thread corrupt. The patch fixes it against kernel 3.9. Signed-off-by: wang, biao <biao.wang@intel.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

klist: del waiter from klist_remove_waiters before wakeup waitting process
There is a race between klist_remove and klist_release. klist_remove uses a local var waiter saved on stack. When klist_release calls wake_up_process(waiter->process) to wake up the waiter, waiter might run immediately and reuse the stack. Then, klist_release calls list_del(&waiter->list) to change previous wait data and cause prior waiter thread corrupt. The patch fixes it against kernel 3.9. Signed-off-by: wang, biao <biao.wang@intel.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
wang, biao · Greg Kroah-Hartman
1 parent 97521978c5
Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff
lib/klist.c
@@ -193,10 +193,10 @@
 		if (waiter->node != n)
 			continue;
  
+		list_del(&waiter->list);
 		waiter->woken = 1;
 		mb();
 		wake_up_process(waiter->process);
-		list_del(&waiter->list);
 	}
 	spin_unlock(&klist_remove_lock);
 	knode_set_klist(n, NULL);
...	...	@@ -193,10 +193,10 @@
193	193	if (waiter->node != n)
194	194	continue;
195	195
	196	+ list_del(&waiter->list);
196	197	waiter->woken = 1;
197	198	mb();
198	199	wake_up_process(waiter->process);
199		- list_del(&waiter->list);
200	200	}
201	201	spin_unlock(&klist_remove_lock);
202	202	knode_set_klist(n, NULL);