netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets
authorFlorian Westphal <fw@strlen.de>
Mon, 19 Feb 2018 00:24:15 +0000 (01:24 +0100)
committerPablo Neira Ayuso <pablo@netfilter.org>
Sun, 25 Feb 2018 19:07:33 +0000 (20:07 +0100)
commitb71812168571fa55e44cdd0254471331b9c4c4c6
tree6dbae0f54e690041491407e6c0dee550fc67a60a
parentfc6a5d0601c5ac1d02f283a46f60b87b2033e5ca
netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets

We need to make sure the offsets are not out of range of the
total size.
Also check that they are in ascending order.

The WARN_ON triggered by syzkaller (it sets panic_on_warn) is
changed to also bail out, no point in continuing parsing.

Briefly tested with simple ruleset of
-A INPUT --limit 1/s' --log
plus jump to custom chains using 32bit ebtables binary.

Reported-by: <syzbot+845a53d13171abf8bf29@syzkaller.appspotmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
net/bridge/netfilter/ebtables.c