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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v4 0/2] blk-cgroup: Fix potential UAF & flush rstat at blkgs destruction path Content-Language: en-US To: Jens Axboe , Tejun Heo , Josef Bacik , Zefan Li , Johannes Weiner , Andrew Morton Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, =?UTF-8?Q?Michal_Koutn=c3=bd?= , "Dennis Zhou (Facebook)" References: <20221215033132.230023-1-longman@redhat.com> From: Waiman Long In-Reply-To: <20221215033132.230023-1-longman@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: A69F418000F X-Rspam-User: X-Stat-Signature: 81994kqmgwopttki7kn86ztobdqhc4u5 X-HE-Tag: 1675308411-729695 X-HE-Meta: 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 wcmXp/fx HAIg7B3U5VIktyG7gbHVDH5QrWiWjK522h4QGeJ6xs2EPgByNAl7V56Ey70odvhpFJFe7mPM1TZOlLj6WTmal2E3e9BDXqmj4DUyqwNklrC6esUWmO+CCW+upbpWJFJAKyugxz7XLYJ7bI2cpwzKECpbhPrh1+Ka+dy0fGR3XRxA3ev0cumYhhJ95nQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 12/14/22 22:31, Waiman Long wrote: > v4: > - Update comment and commit logs for both patches. > > v3: > - Drop v2 patch 2 as it may not be needed. > - Replace css_tryget() with percpu_ref_is_zero() in patch 1 as > suggested by Tejun. > - Expand comment on patch 2 to elaborate the reason for this patch. > > v2: > - Remove unnecessary rcu_read_{lock|unlock} from > cgroup_rstat_css_cpu_flush() in patch 3. > > It was found that blkcg_destroy_blkgs() may be called with all blkcg > references gone. This may potentially cause user-after-free and so should > be fixed. The second patch flushes rstat when calling blkcg_destroy_blkgs(). > > Waiman Long (2): > bdi, blk-cgroup: Fix potential UAF of blkcg > blk-cgroup: Flush stats at blkgs destruction path > > block/blk-cgroup.c | 23 +++++++++++++++++++++++ > include/linux/cgroup.h | 1 + > kernel/cgroup/rstat.c | 18 ++++++++++++++++++ > mm/backing-dev.c | 8 ++++++-- > 4 files changed, 48 insertions(+), 2 deletions(-) > Ping! Any comments on these patches. Thanks, Longman