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Message-ID: <20230124000925.pfosl6pfuhjyggbp@shindev>
Date: Tue, 24 Jan 2023 00:09:25 +0000
From: Shinichiro Kawasaki <shinichiro.kawasaki@....com>
To: Yu Kuai <yukuai3@...wei.com>
CC: "jack@...e.cz" <jack@...e.cz>, "tj@...nel.org" <tj@...nel.org>,
"josef@...icpanda.com" <josef@...icpanda.com>,
"axboe@...nel.dk" <axboe@...nel.dk>,
"paolo.valente@...aro.org" <paolo.valente@...aro.org>,
"cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"yukuai1@...weicloud.com" <yukuai1@...weicloud.com>,
"yi.zhang@...wei.com" <yi.zhang@...wei.com>,
"yangerkun@...wei.com" <yangerkun@...wei.com>
Subject: Re: [PATCH] block, bfq: fix uaf for bfqq in bic_set_bfqq()
On Jan 13, 2023 / 17:44, Yu Kuai wrote:
> After commit 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'"),
> bic->bfqq will be accessed in bic_set_bfqq(), however, in some context
> bic->bfqq will be freed first, and bic_set_bfqq() is called with the freed
> bic->bfqq.
>
> Fix the problem by always freeing bfqq after bic_set_bfqq().
>
> Fixes: 64dc8c732f5c ("block, bfq: fix possible uaf for 'bfqq->bic'")
> Reported-and-tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@....com>
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>
> ---
> block/bfq-cgroup.c | 2 +-
> block/bfq-iosched.c | 4 +++-
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
> index a6e8da5f5cfd..feb13ac25557 100644
> --- a/block/bfq-cgroup.c
> +++ b/block/bfq-cgroup.c
> @@ -749,8 +749,8 @@ static void bfq_sync_bfqq_move(struct bfq_data *bfqd,
> * old cgroup.
> */
> bfq_put_cooperator(sync_bfqq);
> - bfq_release_process_ref(bfqd, sync_bfqq);
> bic_set_bfqq(bic, NULL, true, act_idx);
> + bfq_release_process_ref(bfqd, sync_bfqq);
> }
> }
>
Yu, thanks for posting this fix, but it can not be applied to v6.2-rc5. The
hunk above looks different from the patch I tested. Could you take a look?
--
Shin'ichiro Kawasaki
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