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From: Ben Myers <bpm@sgi.com>
To: Eric Sandeen <sandeen@sandeen.net>, Dave Chinner <david@fromorbit.com>
Cc: kernel-br@googlegroups.com, Alex Elder <elder@kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	"Geyslan G. Bem" <geyslan@gmail.com>,
	XFS FILESYSTEM <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: fix possible NULL dereference
Date: Mon, 21 Oct 2013 18:18:49 -0500	[thread overview]
Message-ID: <20131021231849.GL10553@sgi.com> (raw)
In-Reply-To: <5265B4D2.3000907@sandeen.net>

Hey,

On Mon, Oct 21, 2013 at 06:12:18PM -0500, Eric Sandeen wrote:
> On 10/21/13 5:44 PM, Dave Chinner wrote:
> > On Mon, Oct 21, 2013 at 03:58:23PM -0500, Eric Sandeen wrote:
> >> On 10/21/13 1:32 PM, Geyslan G. Bem wrote:
> >>> This patch puts a 'break' in the true branch, avoiding the 'icptr->ic_next'
> >>> dereferencing.
> >>
> >> Reviewed-by: Eric Sandeen <sandeen@redhat.com>
> > 
> > Actually, NACK.
> 
> I felt that one coming ;)
> 
> >> Hm, yeah - cmn_err(CE_PANIC, " " ); used to BUG_ON, but the newer
> >> xfs_emerg() doesn't.
> >>
> >> Dave, was that intentional?
> > 
> > Of course it was. ;) xfs_emerg() is only called from the debug code
> > in xlog_verify_iclog(), xlog_verify_tail_lsn and assfail().
> > 
> > In the case of assfail(), it has it's own BUG() call, so it does
> > everything just fine.
> > 
> > In the case of xlog_verify_iclog() when icptr is NULL, it will
> > panic immediately after the message is printed, just like the old
> > code. i.e. this patch isn't fixing anything we need fixed. 
> 
> A BUG() is probably warranted, then.

I tend to agree with Eric on this point.  If we want to crash, I'd rather our
intent be very clear, rather than just see a null ptr deref.  ;)

Regards,
	Ben

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WARNING: multiple messages have this Message-ID (diff)
From: Ben Myers <bpm@sgi.com>
To: Eric Sandeen <sandeen@sandeen.net>, Dave Chinner <david@fromorbit.com>
Cc: Alex Elder <elder@kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	XFS FILESYSTEM <xfs@oss.sgi.com>,
	"Geyslan G. Bem" <geyslan@gmail.com>,
	kernel-br@googlegroups.com
Subject: Re: [PATCH] xfs: fix possible NULL dereference
Date: Mon, 21 Oct 2013 18:18:49 -0500	[thread overview]
Message-ID: <20131021231849.GL10553@sgi.com> (raw)
In-Reply-To: <5265B4D2.3000907@sandeen.net>

Hey,

On Mon, Oct 21, 2013 at 06:12:18PM -0500, Eric Sandeen wrote:
> On 10/21/13 5:44 PM, Dave Chinner wrote:
> > On Mon, Oct 21, 2013 at 03:58:23PM -0500, Eric Sandeen wrote:
> >> On 10/21/13 1:32 PM, Geyslan G. Bem wrote:
> >>> This patch puts a 'break' in the true branch, avoiding the 'icptr->ic_next'
> >>> dereferencing.
> >>
> >> Reviewed-by: Eric Sandeen <sandeen@redhat.com>
> > 
> > Actually, NACK.
> 
> I felt that one coming ;)
> 
> >> Hm, yeah - cmn_err(CE_PANIC, " " ); used to BUG_ON, but the newer
> >> xfs_emerg() doesn't.
> >>
> >> Dave, was that intentional?
> > 
> > Of course it was. ;) xfs_emerg() is only called from the debug code
> > in xlog_verify_iclog(), xlog_verify_tail_lsn and assfail().
> > 
> > In the case of assfail(), it has it's own BUG() call, so it does
> > everything just fine.
> > 
> > In the case of xlog_verify_iclog() when icptr is NULL, it will
> > panic immediately after the message is printed, just like the old
> > code. i.e. this patch isn't fixing anything we need fixed. 
> 
> A BUG() is probably warranted, then.

I tend to agree with Eric on this point.  If we want to crash, I'd rather our
intent be very clear, rather than just see a null ptr deref.  ;)

Regards,
	Ben

  reply	other threads:[~2013-10-21 23:18 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-21 18:32 [PATCH] xfs: fix possible NULL dereference Geyslan G. Bem
2013-10-21 18:32 ` Geyslan G. Bem
2013-10-21 20:58 ` Eric Sandeen
2013-10-21 22:44   ` Dave Chinner
2013-10-21 22:44     ` Dave Chinner
2013-10-21 23:12     ` Eric Sandeen
2013-10-21 23:12       ` Eric Sandeen
2013-10-21 23:18       ` Ben Myers [this message]
2013-10-21 23:18         ` Ben Myers
2013-10-21 23:56         ` Dave Chinner
2013-10-21 23:56           ` Dave Chinner
2013-10-22  0:00           ` Eric Sandeen
2013-10-22  0:00             ` Eric Sandeen
2013-10-22  0:17             ` Dave Chinner
2013-10-22  0:17               ` Dave Chinner
2013-10-22 10:12               ` Geyslan Gregório Bem
2013-10-22 10:12                 ` Geyslan Gregório Bem
2013-10-22 20:39                 ` Dave Chinner
2013-10-22 20:39                   ` Dave Chinner
2013-10-22 20:49                   ` Eric Sandeen
2013-10-22 20:49                     ` Eric Sandeen
2013-10-22 21:03                     ` Dave Chinner
2013-10-22 21:03                       ` Dave Chinner
2013-10-22 21:19                       ` Eric Sandeen
2013-10-22 21:19                         ` Eric Sandeen
2013-10-22 22:02                         ` Dave Chinner
2013-10-22 22:02                           ` Dave Chinner
2013-10-22 22:33                           ` Ben Myers
2013-10-22 22:33                             ` Ben Myers
2013-10-25  9:15                           ` Dave Jones
2013-10-25  9:15                             ` Dave Jones
2013-10-23 10:58                         ` Geyslan Gregório Bem
2013-10-23 10:58                           ` Geyslan Gregório Bem
2013-10-23 20:34                           ` Ben Myers
2013-10-23 20:34                             ` Ben Myers
2013-10-23 20:53                             ` Geyslan Gregório Bem
2013-10-23 20:53                               ` Geyslan Gregório Bem
2013-10-30 20:08                             ` Eric Sandeen
2013-10-30 20:08                               ` Eric Sandeen
2013-10-31 15:55                               ` Ben Myers
2013-10-31 15:55                                 ` Ben Myers
2013-10-31 16:15                                 ` Geyslan Gregório Bem
2013-10-31 16:15                                   ` Geyslan Gregório Bem

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