Linux Ethernet Bridging - Mar 2021 - [Bridge] [PATCH] net: bridge: fix error return code of do_update_counters()

When find_table_lock() returns NULL to t, no error return code of
do_update_counters() is assigned.
To fix this bug, ret is assigned with -ENOENT in this case.

Fixes: 49facff9f925 ("netfilter: ebtables: split update_counters into two
functions")
Reported-by: TOTE Robot <oslab at tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990 at gmail.com>
---
 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 ebe33b60efd6..66c9e4077985 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -1256,8 +1256,10 @@ static int do_update_counters(struct net *net, const char
*name,
 		return -ENOMEM;
 
 	t = find_table_lock(net, name, &ret, &ebt_mutex);
-	if (!t)
+	if (!t) {
+		ret = -ENOENT;
 		goto free_tmp;
+	}
 
 	if (num_counters != t->private->nentries) {
 		ret = -EINVAL;
-- 
2.17.1

Jia-Ju Bai <baijiaju1990 at gmail.com> wrote:
> When find_table_lock() returns NULL to t, no error return code of
> do_update_counters() is assigned.
Its -ENOENT.
>  	t = find_table_lock(net, name, &ret, &ebt_mutex);
                                       ^^^^^

ret is passed to find_table_lock, which passes it to
find_inlist_lock_noload() which will set *ret = -ENOENT
for NULL case.