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-ker...@i-love.sakura.ne.jp>
Signed-off-by: Florian Westphal <f...@strlen.de>
---
 net/bridge/netfilter/ebtables.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 3cad01ac64e4..3a1b94b5c0e5 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2158,7 +2158,9 @@ 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;
 }
 
-- 
2.20.1

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