Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
Date:   Tue, 22 Nov 2022 03:58:34 -0800
In-Reply-To: <55a7be14-6ebc-2ee8-34a2-98781b32e29c@huawei.com>
Message-ID: <000000000000343ab505ee0de486@google.com>
Subject: Re: [syzbot] KASAN: use-after-free Write in expire_timers
From:   syzbot <syzbot+38ee3533e07da8749f85@syzkaller.appspotmail.com>
To:     liaoyu15@huawei.com
Cc:     arnd@arndb.de, catalin.marinas@arm.com, liaoyu15@huawei.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        liwei391@huawei.com, syzkaller-bugs@googlegroups.com,
        will@kernel.org, zhengqi.arch@bytedance.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

> On 2022/11/22 2:35, syzbot wrote:
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    b6e7fdfd6f6a Merge tag 'iommu-fixes-v6.1-rc5' of git://git..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=11c28f95880000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=95fb379f123ba8ce
>> dashboard link: https://syzkaller.appspot.com/bug?extid=38ee3533e07da8749f85
>> compiler:       aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>> userspace arch: arm64
>
> Fix data race between virtual_ncidev_close() and virtual_ncidev_open().
>
> #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

This crash does not have a reproducer. I cannot test it.

> b6e7fdfd6f6a
>
> --- a/drivers/nfc/virtual_ncidev.c
> +++ b/drivers/nfc/virtual_ncidev.c
> @@ -161,12 +161,8 @@ static int virtual_ncidev_close(struct inode *inode,
> struct file *file)
>
>     if (state == virtual_ncidev_enabled) {
>         state = virtual_ncidev_disabling;
> -       mutex_unlock(&nci_mutex);
> -
>         nci_unregister_device(ndev);
>         nci_free_device(ndev);
> -
> -       mutex_lock(&nci_mutex);
>     }
>
>     state = virtual_ncidev_disabled;
> --