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Message-ID: <ca9fefd4-7109-042c-3b25-9eb795141145@huaweicloud.com>
Date: Tue, 21 Feb 2023 15:04:08 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: jack@...e.cz, tj@...nel.org, josef@...icpanda.com, axboe@...nel.dk,
paolo.valente@...aro.org, shinichiro.kawasaki@....com
Cc: cgroups@...r.kernel.org, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, yukuai1@...weicloud.com,
yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH] block, bfq: fix uaf for bfqq in bic_set_bfqq()
Hi, Jens
在 2023/01/13 17:44, Yu Kuai 写道:
> 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);
> }
> }
>
It seems this change is missed in GIT PULL for-6.3. I'll send a seperate
patch to fix this...
Thanks,
Kuai
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