linux-kernel - Re: [PATCH] ext4: Fix timer use-after-free on failed mount

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Message-ID: <172476284017.635532.12571452606052946369.b4-ty@mit.edu>
Date: Tue, 27 Aug 2024 08:47:29 -0400
From: "Theodore Ts'o" <tytso@....edu>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaxi Shen <shenxiaxi26@...il.com>
Cc: "Theodore Ts'o" <tytso@....edu>, skhan@...uxfoundation.org,
        javier.carrasco.cruz@...il.com, syzkaller-bugs@...glegroups.com,
        syzbot+59e0101c430934bc9a36@...kaller.appspotmail.com
Subject: Re: [PATCH] ext4: Fix timer use-after-free on failed mount


On Sun, 14 Jul 2024 21:33:36 -0700, Xiaxi Shen wrote:
> Syzbot has found an ODEBUG bug in ext4_fill_super
> 
> The del_timer_sync function cancels the s_err_report timer,
> which reminds about filesystem errors daily. We should
> guarantee the timer is no longer active before kfree(sbi).
> 
> When filesystem mounting fails, the flow goes to failed_mount3,
> where an error occurs when ext4_stop_mmpd is called, causing
> a read I/O failure. This triggers the ext4_handle_error function
> that ultimately re-arms the timer,
> leaving the s_err_report timer active before kfree(sbi) is called.
> 
> [...]

Applied, thanks!

[1/1] ext4: Fix timer use-after-free on failed mount
      commit: 0ce160c5bdb67081a62293028dc85758a8efb22a

Best regards,
-- 
Theodore Ts'o <tytso@....edu>