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Date:   Tue, 8 Feb 2022 17:14:29 +0100
From:   Jan Kara <>
To:     syzbot <>
Cc:,,,,, Ritesh Harjani <>
Subject: Re: [syzbot] KASAN: use-after-free Read in jbd2_journal_wait_updates

On Tue 08-02-22 04:49:19, syzbot wrote:
> Hello,
> syzbot found the following issue on:
> HEAD commit:    555f3d7be91a Merge tag '5.17-rc3-ksmbd-server-fixes' of gi..
> git tree:       upstream
> console output:
> kernel config:
> dashboard link:
> compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by:

So the syzbot reproducer looks bogus to me but the bug is real.
jbd2_journal_wait_updates() looks at commit_transaction after dropping
j_state_lock and sleeping which is certainly prone to use-after-free

Funnily, Ritesh's removal of t_handle_lock should "fix" the problem by
removing this dereference. So Ritesh, please just add some reference to
syzbot report and maybe a backport to stable would be warranted.


Jan Kara <>

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