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net: sched: fix clsact init error path 

Since in qdisc_create, the destroy op is called when init fails, we
don't do cleanup in init and leave it up to destroy.
This fixes use-after-free when trying to put already freed block.

Fixes: 6e40cf2d4d ("net: sched: use extended variants of block_get/put in ingress and clsact qdiscs")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Pirko 2017-12-15 12:40:12 +01:00 committed by David S. Miller
parent c05fad5713
commit 343723dd51
2 changed files with 3 additions and 7 deletions
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4
net/sched/cls_api.c
View File

@ -351,6 +351,8 @@ void tcf_block_put_ext(struct tcf_block *block, struct Qdisc *q,
{ {
struct tcf_chain *chain; struct tcf_chain *chain;
if (!block)
return;
/* Hold a refcnt for all chains, except 0, so that they don't disappear /* Hold a refcnt for all chains, except 0, so that they don't disappear
* while we are iterating. * while we are iterating.
*/ */
@ -377,8 +379,6 @@ void tcf_block_put(struct tcf_block *block)
{ {
struct tcf_block_ext_info ei = {0, }; struct tcf_block_ext_info ei = {0, };
if (!block)
return;
tcf_block_put_ext(block, block->q, &ei); tcf_block_put_ext(block, block->q, &ei);
} }

6
net/sched/sch_ingress.c
View File

@ -190,7 +190,7 @@ static int clsact_init(struct Qdisc *sch, struct nlattr *opt)
err = tcf_block_get_ext(&q->egress_block, sch, &q->egress_block_info); err = tcf_block_get_ext(&q->egress_block, sch, &q->egress_block_info);
if (err) if (err)
goto err_egress_block_get; return err;
net_inc_ingress_queue(); net_inc_ingress_queue();
net_inc_egress_queue(); net_inc_egress_queue();
@ -198,10 +198,6 @@ static int clsact_init(struct Qdisc *sch, struct nlattr *opt)
sch->flags |= TCQ_F_CPUSTATS; sch->flags |= TCQ_F_CPUSTATS;
return 0; return 0;
err_egress_block_get:
tcf_block_put_ext(q->ingress_block, sch, &q->ingress_block_info);
return err;
} }
static void clsact_destroy(struct Qdisc *sch) static void clsact_destroy(struct Qdisc *sch)