From 2235f2ac75fd2501c251b0b699a9632e80239a6d Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 10 Aug 2015 09:09:13 -0700 Subject: 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: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller diff --git a/net/core/request_sock.c b/net/core/request_sock.c index 87b22c0..b42f0e2 100644 --- a/net/core/request_sock.c +++ b/net/core/request_sock.c @@ -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); } diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 60021d0..05e3145 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -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; } -- cgit v0.10.2