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| author | Benjamin Poirier <bpoirier@suse.de> | 2013-04-29 11:42:13 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-04-30 00:43:54 -0400 |
| commit | 39cc86130bc045d87f525ce7742da308ff757cec (patch) | |
| tree | 28e803dce3877b9f1eb7c8ad74fe58c29764a422 | |
| parent | add05ad4e9f5c4efee9b98535db5efa32b0d0492 (diff) | |
| download | linux-stable-39cc86130bc045d87f525ce7742da308ff757cec.tar.gz linux-stable-39cc86130bc045d87f525ce7742da308ff757cec.tar.bz2 linux-stable-39cc86130bc045d87f525ce7742da308ff757cec.zip | |
unix/dgram: fix peeking with an offset larger than data in queue
Currently, peeking on a unix datagram socket with an offset larger than len of
the data in the sk receive queue returns immediately with bogus data. That's
because *off is not reset between each skb_queue_walk().
This patch fixes this so that the behavior is the same as peeking with no
offset on an empty queue: the caller blocks.
Signed-off-by: Benjamin Poirier <bpoirier@suse.de>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/datagram.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c index 99c4f525b1d9..b5d48ac2a9c1 100644 --- a/net/core/datagram.c +++ b/net/core/datagram.c @@ -78,9 +78,10 @@ static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int syn return autoremove_wake_function(wait, mode, sync, key); } /* - * Wait for a packet.. + * Wait for the last received packet to be different from skb */ -static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) +static int wait_for_more_packets(struct sock *sk, int *err, long *timeo_p, + const struct sk_buff *skb) { int error; DEFINE_WAIT_FUNC(wait, receiver_wake_function); @@ -92,7 +93,7 @@ static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) if (error) goto out_err; - if (!skb_queue_empty(&sk->sk_receive_queue)) + if (sk->sk_receive_queue.prev != skb) goto out; /* Socket shut down? */ @@ -131,9 +132,9 @@ out_noerr: * __skb_recv_datagram - Receive a datagram skbuff * @sk: socket * @flags: MSG_ flags + * @peeked: returns non-zero if this packet has been seen before * @off: an offset in bytes to peek skb from. Returns an offset * within an skb where data actually starts - * @peeked: returns non-zero if this packet has been seen before * @err: error code returned * * Get a datagram skbuff, understands the peeking, nonblocking wakeups @@ -161,7 +162,7 @@ out_noerr: struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, int *peeked, int *off, int *err) { - struct sk_buff *skb; + struct sk_buff *skb, *last; long timeo; /* * Caller is allowed not to check sk->sk_err before skb_recv_datagram() @@ -182,14 +183,17 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, */ unsigned long cpu_flags; struct sk_buff_head *queue = &sk->sk_receive_queue; + int _off = *off; + last = (struct sk_buff *)queue; spin_lock_irqsave(&queue->lock, cpu_flags); skb_queue_walk(queue, skb) { + last = skb; *peeked = skb->peeked; if (flags & MSG_PEEK) { - if (*off >= skb->len && (skb->len || *off || + if (_off >= skb->len && (skb->len || _off || skb->peeked)) { - *off -= skb->len; + _off -= skb->len; continue; } skb->peeked = 1; @@ -198,6 +202,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, __skb_unlink(skb, queue); spin_unlock_irqrestore(&queue->lock, cpu_flags); + *off = _off; return skb; } spin_unlock_irqrestore(&queue->lock, cpu_flags); @@ -207,7 +212,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags, if (!timeo) goto no_packet; - } while (!wait_for_packet(sk, err, &timeo)); + } while (!wait_for_more_packets(sk, err, &timeo, last)); return NULL; |