From: Daniel Borkmann <daniel@iogearbox•net>
To: Cong Wang <xiyou.wangcong@gmail•com>, netdev@vger•kernel.org
Cc: davem@davemloft•net, Jamal Hadi Salim <jhs@mojatatu•com>,
Cong Wang <cwang@twopensource•com>
Subject: Re: [Patch net] act_pedit: check binding before calling tcf_hash_release()
Date: Fri, 31 Jul 2015 13:10:35 +0200 [thread overview]
Message-ID: <55BB57AB.5030003@iogearbox.net> (raw)
In-Reply-To: <1438301541-26192-2-git-send-email-xiyou.wangcong@gmail.com>
On 07/31/2015 02:12 AM, Cong Wang wrote:
> When we share an action within a filter, the bind refcnt
> should increase, therefore we should not call tcf_hash_release().
>
> Cc: Jamal Hadi Salim <jhs@mojatatu•com>
> Cc: Daniel Borkmann <daniel@iogearbox•net>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail•com>
> Signed-off-by: Cong Wang <cwang@twopensource•com>
Seems like this slipped in via commit 1a29321ed045. The ugly thing is that
this leads to a use-after-free.
# tc actions add action pedit munge offset 2 u16 at 0 0f0000000 22 set 11500
# tc actions show action pedit
action order 0: pedit action pass keys 1
index 1 ref 1 bind 0
key #0 at 0: val 00002cec mask ffff0000
# tc filter add dev foo parent 1: bpf bytecode "$FOO" flowid 1:1 action pedit index 1
# tc filter show dev foo
filter parent 1: protocol all pref 49152 bpf
filter parent 1: protocol all pref 49152 bpf handle 0x1 flowid 1:1 bytecode '1,6 0 0 4294967295'
action order 1: pedit action pass keys 1
index 1 ref 1 bind 0
key #0 at 0: val 00002cec mask ffff0000
# tc actions del action pedit index 1
.... and now you can wait for the next egress packet. ;)
Thanks for the fix Cong!
Fixes: 1a29321ed045 ("net_sched: act: Dont increment refcnt on replace")
Acked-by: Daniel Borkmann <daniel@iogearbox•net>
next prev parent reply other threads:[~2015-07-31 11:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-31 0:12 [Patch net] act_mirred: avoid calling tcf_hash_release() when binding Cong Wang
2015-07-31 0:12 ` [Patch net] act_pedit: check binding before calling tcf_hash_release() Cong Wang
2015-07-31 11:10 ` Daniel Borkmann [this message]
2015-07-31 22:23 ` David Miller
2015-07-31 10:06 ` [Patch net] act_mirred: avoid calling tcf_hash_release() when binding Daniel Borkmann
2015-07-31 22:25 ` Cong Wang
2015-07-31 22:33 ` Daniel Borkmann
2015-08-03 21:13 ` David Miller
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