epoll: remember the event if epoll_wait returns -EFAULT

If epoll_wait returns -EFAULT, the event that was being returned when the fault was encountered will be forgotten. This is not a big deal since EFAULT will happen only if a buggy userspace program passes in a bad address, in which case what happens later usually doesn't matter. However, it is easy to remember the event for later, and this patch makes a simple change to do that. Signed-off-by: Tony Battersby <[email protected]> Acked-by: Davide Libenzi <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
Blub · Apr 1, 2009 · d030588 · d030588
1 parent abff55c
commit d030588
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
@@ -1054,8 +1054,10 @@ static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head,
 		 */
 		if (revents) {
 			if (__put_user(revents, &uevent->events) ||
-			    __put_user(epi->event.data, &uevent->data))
+			    __put_user(epi->event.data, &uevent->data)) {
+				list_add(&epi->rdllink, head);
 				return eventcnt ? eventcnt : -EFAULT;
+			}
 			eventcnt++;
 			uevent++;
 			if (epi->event.events & EPOLLONESHOT)