4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 2035f3ff8eaa29cfb5c8e2160b0f6e85eeb21a95 ]

Unlike ip(6)tables ebtables only counts user-defined chains.

The effect is that a 32bit ebtables binary on a 64bit kernel can do
'ebtables -N FOO' only after adding at least one rule, else the request
fails with -EINVAL.

This is a similar fix as done in
3f1e53abff84 ("netfilter: ebtables: don't attempt to allocate 0-sized compat 
array").

Fixes: 7d7d7e02111e9 ("netfilter: compat: reject huge allocation requests")
Reported-by: Francesco Ruggeri <frugg...@arista.com>
Signed-off-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 net/bridge/netfilter/ebtables.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 22e4c15a1fc3..53392ac58b38 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2292,9 +2292,12 @@ static int compat_do_replace(struct net *net, void 
__user *user,
 
        xt_compat_lock(NFPROTO_BRIDGE);
 
-       ret = xt_compat_init_offsets(NFPROTO_BRIDGE, tmp.nentries);
-       if (ret < 0)
-               goto out_unlock;
+       if (tmp.nentries) {
+               ret = xt_compat_init_offsets(NFPROTO_BRIDGE, tmp.nentries);
+               if (ret < 0)
+                       goto out_unlock;
+       }
+
        ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state);
        if (ret < 0)
                goto out_unlock;
-- 
2.19.1



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