From: Hangyu Hua hbh25y@gmail.com
[ Upstream commit a41b17ff9dacd22f5f118ee53d82da0f3e52d5e3 ]
In the case of sk->dccps_qpolicy == DCCPQ_POLICY_PRIO, dccp_qpolicy_full will drop a skb when qpolicy is full. And the lock in dccp_sendmsg is released before sock_alloc_send_skb and then relocked after sock_alloc_send_skb. The following conditions may lead dccp_qpolicy_push to add skb to an already full sk_write_queue:
thread1--->lock thread1--->dccp_qpolicy_full: queue is full. drop a skb thread1--->unlock thread2--->lock thread2--->dccp_qpolicy_full: queue is not full. no need to drop. thread2--->unlock thread1--->lock thread1--->dccp_qpolicy_push: add a skb. queue is full. thread1--->unlock thread2--->lock thread2--->dccp_qpolicy_push: add a skb! thread2--->unlock
Fix this by moving dccp_qpolicy_full.
Fixes: b1308dc015eb ("[DCCP]: Set TX Queue Length Bounds via Sysctl") Signed-off-by: Hangyu Hua hbh25y@gmail.com Link: https://lore.kernel.org/r/20220729110027.40569-1-hbh25y@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/dccp/proto.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/net/dccp/proto.c b/net/dccp/proto.c index a976b4d29892..0ee62506105a 100644 --- a/net/dccp/proto.c +++ b/net/dccp/proto.c @@ -736,11 +736,6 @@ int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
lock_sock(sk);
- if (dccp_qpolicy_full(sk)) { - rc = -EAGAIN; - goto out_release; - } - timeo = sock_sndtimeo(sk, noblock);
/* @@ -759,6 +754,11 @@ int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) if (skb == NULL) goto out_release;
+ if (dccp_qpolicy_full(sk)) { + rc = -EAGAIN; + goto out_discard; + } + if (sk->sk_state == DCCP_CLOSED) { rc = -ENOTCONN; goto out_discard;