[syzbot] Monthly ext4 report (May 2023)

[syzbot]

Hello ext4 maintainers/developers,

This is a 31-day syzbot report for the ext4 subsystem.
All related reports/information can be found at:
https://syzkaller.appspot.com/upstream/s/ext4

During the period, 3 new issues were detected and 10 were fixed.
In total, 46 issues are still open and 106 have been fixed so far.

Some of the still happening issues:

Ref Crashes Repro Title
<1> 124 Yes kernel BUG in ext4_do_writepages
https://syzkaller.appspot.com/bug?extid=d1da16f03614058fdc48
<2> 48 No WARNING in ext4_write_inode (2)
https://syzkaller.appspot.com/bug?extid=748cc361874fca7d33cc
<3> 8 Yes WARNING in ext4_da_update_reserve_space (2)
https://syzkaller.appspot.com/bug?extid=a1232eabd7a3d43d4fb5
<4> 8 Yes kernel BUG in __ext4_journal_stop
https://syzkaller.appspot.com/bug?extid=bdab24d5bf96d57c50b0
<5> 7 Yes kernel BUG in ext4_write_inline_data
https://syzkaller.appspot.com/bug?extid=f4582777a19ec422b517

---
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[Baokun Li]

On 2023/5/30 20:38, syzbot wrote:
> Hello ext4 maintainers/developers,
>
> This is a 31-day syzbot report for the ext4 subsystem.
> All related reports/information can be found at:
> https://syzkaller.appspot.com/upstream/s/ext4
>
> During the period, 3 new issues were detected and 10 were fixed.
> In total, 46 issues are still open and 106 have been fixed so far.
>
> Some of the still happening issues:
>
> Ref Crashes Repro Title
> <1> 124 Yes kernel BUG in ext4_do_writepages
> https://syzkaller.appspot.com/bug?extid=d1da16f03614058fdc48
> <2> 48 No WARNING in ext4_write_inode (2)
> https://syzkaller.appspot.com/bug?extid=748cc361874fca7d33cc
> <3> 8 Yes WARNING in ext4_da_update_reserve_space (2)
> https://syzkaller.appspot.com/bug?extid=a1232eabd7a3d43d4fb5
> <4> 8 Yes kernel BUG in __ext4_journal_stop
> https://syzkaller.appspot.com/bug?extid=bdab24d5bf96d57c50b0
> <5> 7 Yes kernel BUG in ext4_write_inline_data
> https://syzkaller.appspot.com/bug?extid=f4582777a19ec422b517
>
> ---
>

Hello, Theodore!

Patch "[PATCH v2] ext4: fix race condition between buffer write and
page_mkwrite​"
in maillist fixes issues <1>,<4>,<5>.

Patch set "[PATCH v4 00/12] ext4: fix WARNING in
ext4_da_update_reserve_space"
in maillist fixes issues <3>.

These patches have been reviewed, could you have time to merge them in?
I would appreciate it if you could.

Thanks!
--
With Best Regards,
Baokun Li
.

[Theodore Ts'o]

On Thu, Jun 01, 2023 at 10:08:53AM +0800, Baokun Li wrote:
>
> Patch "[PATCH v2] ext4: fix race condition between buffer write and
> page_mkwrite​"
> in maillist fixes issues <1>,<4>,<5>.
>
> Patch set "[PATCH v4 00/12] ext4: fix WARNING in
> ext4_da_update_reserve_space"
> in maillist fixes issues <3>.

Thanks for noting that the fixes are applicable to the above reports.
I've adjusted the commit descrptions to include the necessary
Reported-by: lines, and they are in the ext4 dev tree.

Cheers,

- Ted

[Baokun Li]

Thank you very much for your Applied!

There are many sources of syzkaller issues, and the patches I send out
to fix syzkaller issues add Reported-by to all but the ones that fix issues
reported by our internal syzbot.
However, there may be multiple syzbot reports for the same issue.
So I sorry for not adding the "Reported-by:" for the corresponding issue
above.

Please feel free to give me your feedback if the patches have any problems.

[Theodore Ts'o]

On Sat, Jun 03, 2023 at 10:05:44AM +0800, Baokun Li wrote:
>
> There are many sources of syzkaller issues, and the patches I send out
> to fix syzkaller issues add Reported-by to all but the ones that fix issues
> reported by our internal syzbot.
> However, there may be multiple syzbot reports for the same issue.

Yes, that happens a lot especially for Lockdep reports; depending on
how the reproducer triggers the locks in which order, there can often
be multiple different lockdep signatures, and Syzkaller can't tell
that they are all the same thing.

I tend to focus on syzbot reproducers on the upstream Linux instance,
rather than the Android-5.15 syzkaller instance. And that allows me
to use the ext4 subsystem dashboard available at:

https://syzkaller.appspot.com/upstream/s/ext4

It's against this list of reports that the Monthly ext4 report is
generated. So if people who are submitting fixes against syzkaller
reports, it would be nice if they were to check the ext4 dashboard
above to look for syzbot reports that might be also relevant to your
patch.

Thanks,

- Ted

[Baokun Li]

OK, later to fix any ext4 issue, I will check if the issue is in the ext4
subsystem dashboard.