From: Eric Dumazet <edumazet@google.com>
Date: Wed, 13 Apr 2022 17:35:42 +0000 (-0700)
Subject: net/sched: cls_u32: fix possible leak in u32_init_knode()
X-Git-Tag: v4.19.240~39
X-Git-Url: https://git.fsl.cs.sunysb.edu/?a=commitdiff_plain;h=acff67727dff061f107def4c8c08bacde20d0d40;p=wrapfs-3.14.y.git

net/sched: cls_u32: fix possible leak in u32_init_knode()

[ Upstream commit ec5b0f605b105457f257f2870acad4a5d463984b ]

While investigating a related syzbot report,
I found that whenever call to tcf_exts_init()
from u32_init_knode() is failing, we end up
with an elevated refcount on ht->refcnt

To avoid that, only increase the refcount after
all possible errors have been evaluated.

Fixes: b9a24bb76bf6 ("net_sched: properly handle failure case of tcf_exts_init()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index fe246e03fcd9..5eee26cf9011 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -873,10 +873,6 @@ static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
 	new->flags = n->flags;
 	RCU_INIT_POINTER(new->ht_down, ht);
 
-	/* bump reference count as long as we hold pointer to structure */
-	if (ht)
-		ht->refcnt++;
-
 #ifdef CONFIG_CLS_U32_PERF
 	/* Statistics may be incremented by readers during update
 	 * so we must keep them in tact. When the node is later destroyed
@@ -899,6 +895,10 @@ static struct tc_u_knode *u32_init_knode(struct tcf_proto *tp,
 		return NULL;
 	}
 
+	/* bump reference count as long as we hold pointer to structure */
+	if (ht)
+		ht->refcnt++;
+
 	return new;
 }