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 <tonyb@cybernetics.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index db4365f..c806a0c 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1054,8 +1054,10 @@
*/
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)