[PATCH 30/93] klist: del waiter from klist_remove_waiters before wakeup waitting process

From: Luis Henriques
Date: Tue Jun 18 2013 - 08:03:32 EST -stable review patch. If anyone has any objections, please let me know.


From: "wang, biao" <biao.wang@xxxxxxxxx>

commit ac5a2962b02f57dea76d314ef2521a2170b28ab6 upstream.

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@xxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
lib/klist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/klist.c b/lib/klist.c
index 0874e41..358a368 100644
--- a/lib/klist.c
+++ b/lib/klist.c
@@ -193,10 +193,10 @@ static void klist_release(struct kref *kref)
if (waiter->node != n)

+ list_del(&waiter->list);
waiter->woken = 1;
- list_del(&waiter->list);
knode_set_klist(n, NULL);

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