[PATCH 5.10 04/63] ethtool: fix string set id check

Greg Kroah-Hartman
2021-01-04T16:03:04Z

From: Michal Kubecek <mkubecek@suse.cz>

[ Upstream commit efb796f5571f030743e1d9c662cdebdad724f8c5 ]

Syzbot reported a shift of a u32 by more than 31 in strset_parse_request()
which is undefined behavior. This is caused by range check of string set id
using variable ret (which is always 0 at this point) instead of id (string
set id from request).

Fixes: 71921690f974 ("ethtool: provide string sets with STRSET_GET request")
Reported-by: syzbot+96523fb438937cd01220@syzkaller.appspotmail.com
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Link: https://lore.kernel.org/r/b54ed5c5fd972a59afea3e1badfb36d86df68799.1607952208.git.mkubecek@suse.cz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ethtool/strset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ethtool/strset.c
+++ b/net/ethtool/strset.c
@@ -182,7 +182,7 @@ static int strset_parse_request(struct e
ret = strset_get_id(attr, &id, extack);
if (ret < 0)
return ret;
- if (ret >= ETH_SS_COUNT) {
+ if (id >= ETH_SS_COUNT) {
NL_SET_ERR_MSG_ATTR(extack, attr,
"unknown string set id");
return -EOPNOTSUPP;