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>
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@ -193,10 +193,10 @@ static void klist_release(struct kref *kref)
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if (waiter->node != n)
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continue;
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list_del(&waiter->list);
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waiter->woken = 1;
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mb();
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wake_up_process(waiter->process);
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list_del(&waiter->list);
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}
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spin_unlock(&klist_remove_lock);
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knode_set_klist(n, NULL);
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