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Date:   Fri, 26 Aug 2022 00:02:07 +0530
From:   Siddh Raman Pant <code@siddh.me>
To:     "syzbot" <syzbot+5f8dcabe4a3b2c51c607@syzkaller.appspotmail.com>
Cc:     "akpm" <akpm@linux-foundation.org>, "anton" <anton@tuxera.com>,
        "chenxiaosong2" <chenxiaosong2@huawei.com>,
        "linux-kernel" <linux-kernel@vger.kernel.org>,
        "linux-ntfs-dev" <linux-ntfs-dev@lists.sourceforge.net>,
        "syzkaller-bugs" <syzkaller-bugs@googlegroups.com>,
        "yin31149" <yin31149@gmail.com>
Message-ID: <182d6469a5e.4e1cc3b067845.2722724258679993431@siddh.me>
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References: <0000000000006886bd05e714ec18@google.com>
Subject: Re: [syzbot] KASAN: use-after-free Read in ntfs_attr_find
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On Thu, 25 Aug 2022 23:55:35 +0530  syzbot  wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c40e8341e3b3 Merge tag 'cgroup-for-6.0-rc2-fixes' of git:/..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=161114c7080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=911efaff115942bb
> dashboard link: https://syzkaller.appspot.com/bug?extid=5f8dcabe4a3b2c51c607
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14dd8265080000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11f30033080000
> 
> The issue was bisected to:
> 
> commit 38c9c22a85aeed28d0831f230136e9cf6fa2ed44
> Author: ChenXiaoSong chenxiaosong2@huawei.com>
> Date:   Thu Jul 7 10:53:29 2022 +0000
> 
>     ntfs: fix use-after-free in ntfs_ucsncmp()
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16f6cd8d080000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=15f6cd8d080000
> console output: https://syzkaller.appspot.com/x/log.txt?x=11f6cd8d080000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5f8dcabe4a3b2c51c607@syzkaller.appspotmail.com
> Fixes: 38c9c22a85ae ("ntfs: fix use-after-free in ntfs_ucsncmp()")

This is incorrect. The issue is caused by:
9b75450d6c58 ("fs/ntfs3: Fix memory leak if fill_super failed")

The fix for this can be seen by the two different patches tested by syzbot, which
are listed on the dashboard.

Thanks,
Siddh