[PATCH 4.10 43/62] ipv6: check raw payload size correctly in ioctl

From: Greg Kroah-Hartman
Date: Mon May 01 2017 - 17:39:56 EST

4.10-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
@@ -1174,8 +1174,7 @@ static int rawv6_ioctl(struct sock *sk,
skb = skb_peek(&sk->sk_receive_queue);
if (skb)
- amount = skb_tail_pointer(skb) -
- skb_transport_header(skb);
+ amount = skb->len;
return put_user(amount, (int __user *)arg);