From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Mon, 7 Oct 2019 13:26:29 -0700
Subject: net_sched: fix backward compatibility for TCA_ACT_KIND
Git-commit: 4b793feccae3b06764268377a4030eb774ed924e
Patch-mainline: 5.4-rc4
References: git-fixes

For TCA_ACT_KIND, we have to keep the backward compatibility too,
and rely on nla_strlcpy() to check and terminate the string with
a NUL.

Note for TC actions, nla_strcmp() is already used to compare kind
strings, so we don't need to fix other places.

Fixes: 199ce850ce11 ("net_sched: add policy validation for action attributes")
Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/sched/act_api.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -815,8 +815,7 @@ static bool tcf_action_valid(int action)
 }
 
 static const struct nla_policy tcf_action_policy[TCA_ACT_MAX + 1] = {
-	[TCA_ACT_KIND]		= { .type = NLA_NUL_STRING,
-				    .len = IFNAMSIZ - 1 },
+	[TCA_ACT_KIND]		= { .type = NLA_STRING },
 	[TCA_ACT_INDEX]		= { .type = NLA_U32 },
 	[TCA_ACT_COOKIE]	= { .type = NLA_BINARY,
 				    .len = TC_COOKIE_MAX_SIZE },
@@ -847,7 +846,8 @@ struct tc_action *tcf_action_init_1(stru
 			NL_SET_ERR_MSG(extack, "TC action kind must be specified");
 			goto err_out;
 		}
-		nla_strlcpy(act_name, kind, IFNAMSIZ);
+		if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ)
+			goto err_out;
 
 		if (tb[TCA_ACT_COOKIE]) {
 			cookie = nla_memdup_cookie(tb);