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

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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: b9a24bb76b ("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>
This commit is contained in:
Eric Dumazet 2022-04-13 10:35:42 -07:00 committed by Jakub Kicinski
parent 3db09e762d
commit ec5b0f605b
1 changed files with 4 additions and 4 deletions
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8
net/sched/cls_u32.c
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@ -815,10 +815,6 @@ static struct tc_u_knode *u32_init_knode(struct net *net, 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
@ -840,6 +836,10 @@ static struct tc_u_knode *u32_init_knode(struct net *net, struct tcf_proto *tp,
return NULL;
}
/* bump reference count as long as we hold pointer to structure */
if (ht)
ht->refcnt++;
return new;
}