From: Eric Sandeen <sandeen@sandeen.net>
To: Christoph Hellwig <hch@infradead.org>, Brian Foster <bfoster@redhat.com>
Cc: Eric Sandeen <sandeen@redhat.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: fix buffer use after free on IO error
Date: Tue, 25 Mar 2014 09:05:04 -0700 [thread overview]
Message-ID: <5331A930.9030402@sandeen.net> (raw)
In-Reply-To: <20140325131705.GB25392@infradead.org>
On 3/25/14, 6:17 AM, Christoph Hellwig wrote:
>> On Fri, Mar 21, 2014 at 09:48:50PM -0500, Eric Sandeen wrote:
>>> + /*
>>> + * If _xfs_buf_ioapply failed, we'll get back here with
>>> + * only the reference we took above. _xfs_buf_ioend will
>>> + * drop it to zero, so we'd better not queue it for later,
>>> + * or we'll free it before it's done.
>>> + */
>>> + _xfs_buf_ioend(bp, bp->b_error ? 0 : 1);
>>>
>>
>> Out of curiosity, is there any major reason we don't use 0 here
>> unconditionally? Are we worried about I/O completing before we have a
>> chance to decrement the reference?
>
> I think this should unconditionally avoid the schedule, and while we're
> at it we should kill _xfs_buf_ioend and opencode it here and at the
> other callsite.
And then remove the flag from xfs_buf_ioend which is always 0 at that
point ...
> Also atomic_dec_and_test really just returns true/false - there should
> ne no need for the explicit == 1 in the conditional.
Yeah I have a patch to do that as well; I wanted to separate the
bugfix from the more invasive cleanup, though - and I wanted to
get the fix out for review sooner.
But yeah, I was unsure about whether or not to schedule at all here.
We come here from a lot of callsites and I'm honestly not sure what
the implications are yet.
-Eric
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2014-03-25 16:05 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-22 2:48 [PATCH] xfs: fix buffer use after free on IO error Eric Sandeen
2014-03-25 12:58 ` Brian Foster
2014-03-25 13:17 ` Christoph Hellwig
2014-03-25 16:05 ` Eric Sandeen [this message]
2014-03-25 17:25 ` Christoph Hellwig
2014-03-25 17:39 ` Eric Sandeen
2014-03-25 17:44 ` Christoph Hellwig
2014-03-25 18:08 ` Dave Chinner
2014-03-25 18:13 ` Christoph Hellwig
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=5331A930.9030402@sandeen.net \
--to=sandeen@sandeen.net \
--cc=bfoster@redhat.com \
--cc=hch@infradead.org \
--cc=sandeen@redhat.com \
--cc=xfs@oss.sgi.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox