From: Nikolay Borisov <nborisov@suse.com>
To: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
David Sterba <dsterba@suse.com>
Cc: "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
Anand Jain <anand.jain@oracle.com>,
"syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com"
<syzbot+582e66e5edf36a22c7b0@syzkaller.appspotmail.com>
Subject: Re: [PATCH] btrfs: don't access possibly stale fs_info data for printing duplicate device
Date: Thu, 12 Nov 2020 14:25:19 +0200 [thread overview]
Message-ID: <469df3f6-33bd-e725-a3fb-ac77ca852149@suse.com> (raw)
In-Reply-To: <SN4PR0401MB35987501AB13F33A9498D85D9BE70@SN4PR0401MB3598.namprd04.prod.outlook.com>
On 12.11.20 г. 14:09 ч., Johannes Thumshirn wrote:
> On 12/11/2020 13:03, Nikolay Borisov wrote:
>> Would a simple 'if()' here catch the case where fs_info is not
>> initialized essentially open-coding what Anand has proposed? My idea is
>> to be able to provide the filesystem id when we can (best effort) and
>> simply use pr_warn otherwise, but without having to change the internals
>> of btrfs_printk and instead handle the single problematic call site ?
>>
>
> Unfortunately not, I've been trying to do that but the device->fs_info pointer
> exists and accessing it triggers a KASAN splat.
>
> Actually btrfs_printk() is already checking if fs_info is NULL or not to decide
> whether to print <unknown> or fs_info->sb->s_id.
>
> Another option would be to do btrfs_warn_in_rcu(NULL but that doesn't buy us a lot
> more.
>
Indeed, so I'm fine to proceed with this simpler code.
next prev parent reply other threads:[~2020-11-12 12:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 11:59 [PATCH] btrfs: don't access possibly stale fs_info data for printing duplicate device Johannes Thumshirn
2020-11-12 12:02 ` Nikolay Borisov
2020-11-12 12:09 ` Johannes Thumshirn
2020-11-12 12:25 ` Nikolay Borisov [this message]
2020-11-13 16:53 ` David Sterba
2020-11-13 16:57 ` David Sterba
2020-11-13 18:41 ` Johannes Thumshirn
2020-11-13 18:45 ` Johannes Thumshirn
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