Commit 83fccfc3 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

inet: fix potential deadlock in reqsk_queue_unlink()

When replacing del_timer() with del_timer_sync(), I introduced
a deadlock condition :

reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop()

inet_csk_reqsk_queue_drop() can be called from many contexts,
one being the timer handler itself (reqsk_timer_handler()).

In this case, del_timer_sync() loops forever.

Simple fix is to test if timer is pending.

Fixes: 2235f2ac ("inet: fix races with reqsk timers")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2a4eebf0
...@@ -593,7 +593,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue, ...@@ -593,7 +593,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue,
} }
spin_unlock(&queue->syn_wait_lock); spin_unlock(&queue->syn_wait_lock);
if (del_timer_sync(&req->rsk_timer)) if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
reqsk_put(req); reqsk_put(req);
return found; return found;
} }
......
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