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| author |   Paolo Abeni <pabeni@redhat.com> | 2017-02-21 09:33:18 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-02-21 12:23:53 -0500 |
| commit | ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32 (patch) | |
| tree | 0e9ae821b92bfa2cb2e143e15b4b98e829d59528 | |
| parent | vxlan: remove unused variable saddr in neigh_reduce (diff) | |
| download | linux-dev-ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32.tar.xz linux-dev-ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32.zip | |
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>
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 8 |
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) return; - 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); } |