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Commit 2235f2ac authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

inet: fix races with reqsk timers 



reqsk_queue_destroy() and reqsk_queue_unlink() should use
del_timer_sync() instead of del_timer() before calling reqsk_put(),
otherwise we could free a req still used by another cpu.

But before doing so, reqsk_queue_destroy() must release syn_wait_lock
spinlock or risk a dead lock, as reqsk_timer_handler() might
need to take this same spinlock from reqsk_queue_unlink() (called from
inet_csk_reqsk_queue_drop())

Fixes: fa76ce73 ("inet: get rid of central tcp/dccp listener timer")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9d332d92

net/core/request_sock.c

+7 −1
Original line number Diff line number Diff line
@@ -103,10 +103,16 @@ void reqsk_queue_destroy(struct request_sock_queue *queue) 
			spin_lock_bh(&queue->syn_wait_lock);

			while ((req = lopt->syn_table[i]) != NULL) {

				lopt->syn_table[i] = req->dl_next;

				/* Because of following del_timer_sync(),

				 * we must release the spinlock here

				 * or risk a dead lock.

				 */

				spin_unlock_bh(&queue->syn_wait_lock);

				atomic_inc(&lopt->qlen_dec);

				if (del_timer(&req->rsk_timer))

				if (del_timer_sync(&req->rsk_timer))

					reqsk_put(req);

				reqsk_put(req);

				spin_lock_bh(&queue->syn_wait_lock);

			}

			spin_unlock_bh(&queue->syn_wait_lock);

		}

net/ipv4/inet_connection_sock.c

+1 −1
Original line number Diff line number Diff line
@@ -593,7 +593,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue, 
	}



	spin_unlock(&queue->syn_wait_lock);

	if (del_timer(&req->rsk_timer))

	if (del_timer_sync(&req->rsk_timer))

		reqsk_put(req);

	return found;

}