path: root/net/ipv4/ip_sockglue.c
diff options
authorPaolo Abeni <pabeni@redhat.com>2017-02-21 09:33:18 +0100
committerDavid S. Miller <davem@davemloft.net>2017-02-21 12:23:53 -0500
commitca4ef4574f1ee5252e2cd365f8f5d5bafd048f32 (patch)
tree0e9ae821b92bfa2cb2e143e15b4b98e829d59528 /net/ipv4/ip_sockglue.c
parentvxlan: remove unused variable saddr in neigh_reduce (diff)
ip: fix IP_CHECKSUM handling
The skbs processed by ip_cmsg_recv() are not guaranteed to be linear e.g. when sending UDP packets over loopback with MSGMORE. Using csum_partial() on [potentially] the whole skb len is dangerous; instead be on the safe side and use skb_checksum(). Thanks to syzkaller team to detect the issue and provide the reproducer. v1 -> v2: - move the variable declaration in a tighter scope Fixes: ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv") Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_sockglue.c')
1 files changed, 4 insertions, 4 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ce1386a67e24..ebd953bc5607 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -116,10 +116,10 @@ static void ip_cmsg_recv_checksum(struct msghdr *msg, struct sk_buff *skb,
if (skb->ip_summed != CHECKSUM_COMPLETE)
- if (offset != 0)
- csum = csum_sub(csum,
- csum_partial(skb_transport_header(skb) + tlen,
- offset, 0));
+ if (offset != 0) {
+ int tend_off = skb_transport_offset(skb) + tlen;
+ csum = csum_sub(csum, skb_checksum(skb, tend_off, offset, 0));
+ }
put_cmsg(msg, SOL_IP, IP_CHECKSUM, sizeof(__wsum), &csum);