4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jamie Bainbridge <jbainbri@xxxxxxxxxx> [ Upstream commit 105f5528b9bbaa08b526d3405a5bcd2ff0c953c8 ] In situations where an skb is paged, the transport header pointer and tail pointer can be the same because the skb contents are in frags. This results in ioctl(SIOCINQ/FIONREAD) incorrectly returning a length of 0 when the length to receive is actually greater than zero. skb->len is already correctly set in ip6_input_finish() with pskb_pull(), so use skb->len as it always returns the correct result for both linear and paged data. Signed-off-by: Jamie Bainbridge <jbainbri@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/raw.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -1144,8 +1144,7 @@ static int rawv6_ioctl(struct sock *sk, spin_lock_bh(&sk->sk_receive_queue.lock); skb = skb_peek(&sk->sk_receive_queue); if (skb) - amount = skb_tail_pointer(skb) - - skb_transport_header(skb); + amount = skb->len; spin_unlock_bh(&sk->sk_receive_queue.lock); return put_user(amount, (int __user *)arg); }