netfilter: ebtables: CONFIG_COMPAT: reject trailing data after last rule

commit 680f6af5337c98d116e4f127cea7845339dba8da upstream.

If userspace provides a rule blob with trailing data after last target,
we trigger a splat, then convert ruleset to 64bit format (with trailing
data), then pass that to do_replace_finish() which then returns -EINVAL.

Erroring out right away avoids the splat plus unneeded translation and
error unwind.

Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 75929f9bd4e6b26497a51073742ef473c8deb28a..1596736ff268a363261ac116a8716b48f14cac40 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2139,7 +2139,9 @@ static int compat_copy_entries(unsigned char *data, unsigned int size_user,
        if (ret < 0)
                return ret;
 
-       WARN_ON(size_remaining);
+       if (size_remaining)
+               return -EINVAL;
+
        return state->buf_kern_offset;
 }