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Subject: Re: KASAN: use-after-free Read in idr_for_each
To:     syzbot <syzbot+25d82ed5cc4b474f1df8@syzkaller.appspotmail.com>,
        io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        viro@zeniv.linux.org.uk
References: <00000000000093837f05acc5a11f@google.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <45954f2a-bd4a-7188-0013-a48efb2a3a50@kernel.dk>
Date:   Thu, 13 Aug 2020 12:43:50 -0600
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On 8/13/20 11:28 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    fb893de3 Merge tag 'tag-chrome-platform-for-v5.9' of git:/..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=167ed216900000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f1fedc63022bf07e
> dashboard link: https://syzkaller.appspot.com/bug?extid=25d82ed5cc4b474f1df8
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=107bc222900000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17a09d06900000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+25d82ed5cc4b474f1df8@syzkaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: use-after-free in radix_tree_next_slot include/linux/radix-tree.h:421 [inline]
> BUG: KASAN: use-after-free in idr_for_each+0x206/0x220 lib/idr.c:202
> Read of size 8 at addr ffff888082058c78 by task syz-executor999/3765

Should already be fixed by:

commit 6d816e088c359866f9867057e04f244c608c42fe
Author: Jens Axboe <axboe@kernel.dk>
Date:   Tue Aug 11 08:04:14 2020 -0600

    io_uring: hold 'ctx' reference around task_work queue + execute

which is going upstream soon.

#syz dup: KASAN: use-after-free Read in io_async_task_func

-- 
Jens Axboe