From: Eric Dumazet Date: Mon, 10 Aug 2015 16:09:13 +0000 (-0700) Subject: inet: fix races with reqsk timers X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2235f2ac75fd;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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 87b22c0bc08c..b42f0e26f89e 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 60021d0d9326..05e3145f7dc3 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; }