Date: Tue, 2 Jul 2024 20:25:06 +0800
From: Baokun Li <libaokun@...weicloud.com>
To: netfs@...ts.linux.dev, dhowells@...hat.com, jlayton@...nel.org
Cc: hsiangkao@...ux.alibaba.com, jefflexu@...ux.alibaba.com,
 zhujia.zj@...edance.com, linux-erofs@...ts.ozlabs.org, brauner@...nel.org,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 yangerkun@...wei.com, houtao1@...wei.com, yukuai3@...wei.com,
 wozizhi@...wei.com, Baokun Li <libaokun1@...wei.com>,
 Baokun Li <libaokun@...weicloud.com>
Subject: Re: [PATCH v3 0/9] cachefiles: random bugfixes

Friendly ping...

On 2024/6/28 14:29, libaokun@...weicloud.com wrote:
> From: Baokun Li <libaokun1@...wei.com>
>
> Hi all!
>
> This is the third version of this patch series, in which another patch set
> is subsumed into this one to avoid confusing the two patch sets.
> (https://patchwork.kernel.org/project/linux-fsdevel/list/?series=854914)
>
> Thank you, Jia Zhu, Gao Xiang, Jeff Layton, for the feedback in the
> previous version.
>
> We've been testing ondemand mode for cachefiles since January, and we're
> almost done. We hit a lot of issues during the testing period, and this
> patch series fixes some of the issues. The patches have passed internal
> testing without regression.
>
> The following is a brief overview of the patches, see the patches for
> more details.
>
> Patch 1-2: Add fscache_try_get_volume() helper function to avoid
> fscache_volume use-after-free on cache withdrawal.
>
> Patch 3: Fix cachefiles_lookup_cookie() and cachefiles_withdraw_cache()
> concurrency causing cachefiles_volume use-after-free.
>
> Patch 4: Propagate error codes returned by vfs_getxattr() to avoid
> endless loops.
>
> Patch 5-7: A read request waiting for reopen could be closed maliciously
> before the reopen worker is executing or waiting to be scheduled. So
> ondemand_object_worker() may be called after the info and object and even
> the cache have been freed and trigger use-after-free. So use
> cancel_work_sync() in cachefiles_ondemand_clean_object() to cancel the
> reopen worker or wait for it to finish. Since it makes no sense to wait
> for the daemon to complete the reopen request, to avoid this pointless
> operation blocking cancel_work_sync(), Patch 1 avoids request generation
> by the DROPPING state when the request has not been sent, and Patch 2
> flushes the requests of the current object before cancel_work_sync().
>
> Patch 8: Cyclic allocation of msg_id to avoid msg_id reuse misleading
> the daemon to cause hung.
>
> Patch 9: Hold xas_lock during polling to avoid dereferencing reqs causing
> use-after-free. This issue was triggered frequently in our tests, and we
> found that anolis 5.10 had fixed it. So to avoid failing the test, this
> patch is pushed upstream as well.
>
> Comments and questions are, as always, welcome.
> Please let me know what you think.
>
> Thanks,
> Baokun
>
> Changes since v2:
>    * Collect Acked-by from Jeff Layton.(Thanks for your ack!)
>    * Collect RVB from Gao Xiang.(Thanks for your review!)
>    * Patch 1-4 from another patch set.
>    * Pathch 4,6,7: Optimise commit messages and subjects.
>
> Changes since v1:
>    * Collect RVB from Jia Zhu and Gao Xiang.(Thanks for your review!)
>    * Pathch 1,2：Add more commit messages.
>    * Pathch 3：Add Fixes tag as suggested by Jia Zhu.
>    * Pathch 4：No longer changing "do...while" to "retry" to focus changes
>      and optimise commit messages.
>    * Pathch 5: Drop the internal RVB tag.
>
> v1: https://lore.kernel.org/all/20240424033409.2735257-1-libaokun@huaweicloud.com
> v2: https://lore.kernel.org/all/20240515125136.3714580-1-libaokun@huaweicloud.com
>
> Baokun Li (7):
>    netfs, fscache: export fscache_put_volume() and add
>      fscache_try_get_volume()
>    cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
>    cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()
>    cachefiles: propagate errors from vfs_getxattr() to avoid infinite
>      loop
>    cachefiles: stop sending new request when dropping object
>    cachefiles: cancel all requests for the object that is being dropped
>    cachefiles: cyclic allocation of msg_id to avoid reuse
>
> Hou Tao (1):
>    cachefiles: wait for ondemand_object_worker to finish when dropping
>      object
>
> Jingbo Xu (1):
>    cachefiles: add missing lock protection when polling
>
>   fs/cachefiles/cache.c          | 45 ++++++++++++++++++++++++++++-
>   fs/cachefiles/daemon.c         |  4 +--
>   fs/cachefiles/internal.h       |  3 ++
>   fs/cachefiles/ondemand.c       | 52 ++++++++++++++++++++++++++++++----
>   fs/cachefiles/volume.c         |  1 -
>   fs/cachefiles/xattr.c          |  5 +++-
>   fs/netfs/fscache_volume.c      | 14 +++++++++
>   fs/netfs/internal.h            |  2 --
>   include/linux/fscache-cache.h  |  6 ++++
>   include/trace/events/fscache.h |  4 +++
>   10 files changed, 123 insertions(+), 13 deletions(-)
>

-- 
With Best Regards,
Baokun Li

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