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authorEric Dumazet <edumazet@google.com>2015-08-10 09:09:13 -0700
committerDavid S. Miller <davem@davemloft.net>2015-08-10 21:17:29 -0700
commit2235f2ac75fd2501c251b0b699a9632e80239a6d (patch)
tree1d332db260b2a933ac42386c254d0d14163a1d84 /net/core
parent9d332d92a95c9c67abe08b5f7cba64d8fc1e3c76 (diff)
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 <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/request_sock.c8
1 files changed, 7 insertions, 1 deletions
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);
}

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