From: Vlad Buslov <vladbu@nvidia•com>
To: Eric Dumazet <edumazet@google•com>
Cc: Eric Dumazet <eric.dumazet@gmail•com>,
"David S . Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>, netdev <netdev@vger•kernel.org>,
Vlad Buslov <vladbu@mellanox•com>, Jiri Pirko <jiri@mellanox•com>,
Cong Wang <xiyou.wangcong@gmail•com>,
syzbot <syzkaller@googlegroups•com>
Subject: Re: [PATCH net] net: sched: fix use-after-free in tc_new_tfilter()
Date: Mon, 31 Jan 2022 21:36:23 +0200 [thread overview]
Message-ID: <ygnhtudjofyg.fsf@nvidia.com> (raw)
In-Reply-To: <CANn89iL7_FtnUmTxY=tN5dQuB82QL=LANXKxo+vwO90yu1fcJg@mail.gmail.com>
On Mon 31 Jan 2022 at 21:31, Eric Dumazet <edumazet@google•com> wrote:
> On Mon, Jan 31, 2022 at 11:28 AM Vlad Buslov <vladbu@nvidia•com> wrote:
>>
>> Yeah, but I also didn't get how the "chain" variable can get reused in
>> that other function (tcf_new_tfilter()). It seems to always be
>> unconditionally assigned with return value of tcf_chain_get().
>>
>
> This is why I removed the chain=NULL initialization which is not needed.
>
> The potential issue about replay was really about @q variable.
Got it. Initially it wasn't clear because I got the impression from
commit message that reuse of both variables can lead to use-after-free:
"we need to make sure @q and @chain local variables are cleared again,
or risk use-after-free".
next prev parent reply other threads:[~2022-01-31 19:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-31 17:20 [PATCH net] net: sched: fix use-after-free in tc_new_tfilter() Eric Dumazet
2022-01-31 18:53 ` Vlad Buslov
2022-01-31 19:08 ` Eric Dumazet
2022-01-31 19:28 ` Vlad Buslov
2022-01-31 19:31 ` Eric Dumazet
2022-01-31 19:36 ` Vlad Buslov [this message]
2022-02-02 4:20 ` patchwork-bot+netdevbpf
2022-04-01 7:33 ` Denis Efremov
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