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authorEric Dumazet <edumazet@google.com>2016-08-23 23:59:33 +0300
committerDavid S. Miller <davem@davemloft.net>2016-08-24 02:39:14 +0300
commite83c6744e81abc93a20d0eb3b7f504a176a6126a (patch)
treedee57e012d013ab817eb69dd6d1b8a277052e366 /net/ipv4/udp.c
parent28a10c426e81afc88514bca8e73affccf850fdf6 (diff)
downloadlinux-e83c6744e81abc93a20d0eb3b7f504a176a6126a.tar.xz
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.c12
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;