LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Eric Biggers <ebiggers@kernel.org>
To: Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	David Sterba <dsterba@suse.com>,
	linux-btrfs@vger.kernel.org
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Anand Jain <anand.jain@oracle.com>,
	syzbot <syzbot+5b658d997a83984507a6@syzkaller.appspotmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: kernel BUG at fs/btrfs/volumes.c:LINE!
Date: Mon, 10 Jun 2019 16:14:04 -0700	[thread overview]
Message-ID: <20190610231403.GZ63833@gmail.com> (raw)
In-Reply-To: <20180607165213.GI3215@twin.jikos.cz>

On Thu, Jun 07, 2018 at 06:52:13PM +0200, David Sterba wrote:
> On Thu, Jun 07, 2018 at 06:28:02PM +0200, Dmitry Vyukov wrote:
> > > Normally the GFP_NOFS allocations do not fail so I think the fuzzer
> > > environment is tuned to allow that, which is fine for coverage but does
> > > not happen in practice. This will be fixed eventually.
> > 
> > Isn't GFP_NOFS more restricted than normal allocations?  Are these
> > allocations accounted against memcg? It's easy to fail any allocation
> > within a memory container.
> 
> https://lwn.net/Articles/723317/ The 'too small to fail' and some
> unwritten semantics of GFP_NOFS but I think you're right about the
> memory controler that can fail any allocation though.
> 
> Error handling is being improved over time, the memory allocation
> failures are in some cases hard and this one would need to update some
> logic so it's not a oneliner.
> 

This bug is still there.  In btrfs_close_one_device():

	if (device->name) {
		name = rcu_string_strdup(device->name->str, GFP_NOFS);
		BUG_ON(!name); /* -ENOMEM */
		rcu_assign_pointer(new_device->name, name);
	}

It assumes that the memory allocation succeeded.

See syzbot report from v5.2-rc3 here: https://syzkaller.appspot.com/text?tag=CrashReport&x=16c839c1a00000

Is there any plan to fix this?

- Eric

  reply	other threads:[~2019-06-10 23:14 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-06 13:31 syzbot
2018-06-06 16:15 ` Anand Jain
2018-06-07 15:34   ` David Sterba
2018-06-07 16:28     ` Dmitry Vyukov
2018-06-07 16:52       ` David Sterba
2019-06-10 23:14         ` Eric Biggers [this message]
2019-06-11 10:01           ` David Sterba
2019-12-04 14:59 ` Johannes Thumshirn
2019-12-05 10:00   ` Johannes Thumshirn
2019-12-05 10:07     ` Dmitry Vyukov
2019-12-05 10:07       ` syzbot
2019-12-05 11:38       ` Johannes Thumshirn
2019-12-05 11:50         ` David Sterba
2019-12-05 12:06           ` Dmitry Vyukov
2019-12-10 15:11             ` Dmitry Vyukov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190610231403.GZ63833@gmail.com \
    --to=ebiggers@kernel.org \
    --cc=anand.jain@oracle.com \
    --cc=clm@fb.com \
    --cc=dsterba@suse.com \
    --cc=dvyukov@google.com \
    --cc=josef@toxicpanda.com \
    --cc=linux-btrfs@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=syzbot+5b658d997a83984507a6@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --subject='Re: kernel BUG at fs/btrfs/volumes.c:LINE'\!'' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).