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| author | Eric Dumazet <edumazet@google.com> | 2016-08-23 13:59:33 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-08-23 16:39:14 -0700 |
| commit | e83c6744e81abc93a20d0eb3b7f504a176a6126a (patch) | |
| tree | dee57e012d013ab817eb69dd6d1b8a277052e366 /net/ipv4/udp.c | |
| parent | 28a10c426e81afc88514bca8e73affccf850fdf6 (diff) | |
| download | lwn-e83c6744e81abc93a20d0eb3b7f504a176a6126a.tar.gz lwn-e83c6744e81abc93a20d0eb3b7f504a176a6126a.zip | |
udp: fix poll() issue with zero sized packets
Laura tracked poll() [and friends] regression caused by commit
e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")
udp_poll() needs to know if there is a valid packet in receive queue,
even if its payload length is 0.
Change first_packet_length() to return an signed int, and use -1
as the indication of an empty queue.
Fixes: e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")
Reported-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/udp.c')
| -rw-r--r-- | net/ipv4/udp.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index e61f7cd65d08..00d18c57c83c 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1182,13 +1182,13 @@ out: * @sk: socket * * Drops all bad checksum frames, until a valid one is found. - * Returns the length of found skb, or 0 if none is found. + * Returns the length of found skb, or -1 if none is found. */ -static unsigned int first_packet_length(struct sock *sk) +static int first_packet_length(struct sock *sk) { struct sk_buff_head list_kill, *rcvq = &sk->sk_receive_queue; struct sk_buff *skb; - unsigned int res; + int res; __skb_queue_head_init(&list_kill); @@ -1203,7 +1203,7 @@ static unsigned int first_packet_length(struct sock *sk) __skb_unlink(skb, rcvq); __skb_queue_tail(&list_kill, skb); } - res = skb ? skb->len : 0; + res = skb ? skb->len : -1; spin_unlock_bh(&rcvq->lock); if (!skb_queue_empty(&list_kill)) { @@ -1232,7 +1232,7 @@ int udp_ioctl(struct sock *sk, int cmd, unsigned long arg) case SIOCINQ: { - unsigned int amount = first_packet_length(sk); + int amount = max_t(int, 0, first_packet_length(sk)); return put_user(amount, (int __user *)arg); } @@ -2184,7 +2184,7 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait) /* Check for false positives due to checksum errors */ if ((mask & POLLRDNORM) && !(file->f_flags & O_NONBLOCK) && - !(sk->sk_shutdown & RCV_SHUTDOWN) && !first_packet_length(sk)) + !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1) mask &= ~(POLLIN | POLLRDNORM); return mask; |