[PATCH nf] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

[PATCH nf] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

[Florian Westphal]

It means userspace gave us a ruleset where there is some other
data after the ebtables target but before the beginning of the next rule.

Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support")
Reported-by: syzbot+659574e7bcc7f7eb4df7@syzkaller.appspotmail.com
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/bridge/netfilter/ebtables.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index eb15891f8b9f..3cad01ac64e4 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2032,7 +2032,8 @@ static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32,
 		if (match_kern)
 			match_kern->match_size = ret;
 
-		if (WARN_ON(type == EBT_COMPAT_TARGET && size_left))
+		/* rule should have no remaining data after target */
+		if (type == EBT_COMPAT_TARGET && size_left)
 			return -EINVAL;
 
 		match32 = (struct compat_ebt_entry_mwt *) buf;
-- 
2.21.0

Re: [PATCH nf] netfilter: ebtables: CONFIG_COMPAT: drop a bogus WARN_ON

[Pablo Neira Ayuso]

On Mon, Apr 15, 2019 at 12:43:00AM +0200, Florian Westphal wrote:
> It means userspace gave us a ruleset where there is some other
> data after the ebtables target but before the beginning of the next rule.

Applied, thanks Florian.