net: fix nla_strcmp to handle more then one trailing null character

[ Upstream commit 2c16db6c92b0ee4aa61e88366df82169e83c3f7e ]

Android userspace has been using TCA_KIND with a char[IFNAMESIZ]
many-null-terminated buffer containing the string 'bpf'.

This works on 4.19 and ceases to work on 5.10.

I'm not entirely sure what fixes tag to use, but I think the issue
was likely introduced in the below mentioned 5.4 commit.

Reported-by: Nucca Chen <nuccachen@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@mellanox.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Fixes: 62794fc4fb ("net_sched: add max len check for TCA_KIND")
Change-Id: I66dc281f165a2858fc29a44869a270a2d698a82b
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Maciej Żenczykowski 2021-05-05 09:58:31 -07:00 committed by Greg Kroah-Hartman
parent 26b7924707
commit d6c635a8cc

View File

@ -816,7 +816,7 @@ int nla_strcmp(const struct nlattr *nla, const char *str)
int attrlen = nla_len(nla); int attrlen = nla_len(nla);
int d; int d;
if (attrlen > 0 && buf[attrlen - 1] == '\0') while (attrlen > 0 && buf[attrlen - 1] == '\0')
attrlen--; attrlen--;
d = attrlen - len; d = attrlen - len;