This is a note to let you know that I've just added the patch titled
ip: fix IP_CHECKSUM handling
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ip-fix-ip_checksum-handling.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 23 21:13:19 CET 2017
From: Paolo Abeni <pabeni@xxxxxxxxxx>
Date: Tue, 21 Feb 2017 09:33:18 +0100
Subject: ip: fix IP_CHECKSUM handling
From: Paolo Abeni <pabeni@xxxxxxxxxx>
[ Upstream commit ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32 ]
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@xxxxxxxxxx>
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/ip_sockglue.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -105,10 +105,10 @@ static void ip_cmsg_recv_checksum(struct
if (skb->ip_summed != CHECKSUM_COMPLETE)
return;
- if (offset != 0)
- csum = csum_sub(csum,
- csum_partial(skb->data + 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);
}
Patches currently in stable-queue which might be from pabeni@xxxxxxxxxx are
queue-4.4/ip-fix-ip_checksum-handling.patch