linux-kernel - Re: [PATCH] Check for Null return of function of affs_bread in function affs

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Date:	Fri, 20 Jun 2014 22:25:47 -0400
From:	Nick Krause <xerofoify@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Dan Carpenter <dan.carpenter@...cle.com>,
	akpm@...ux-foundation.org, viro@...iv.linux.org.uk, fabf@...net.be,
	kirill.shutemov@...ux.intel.com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Check for Null return of function of affs_bread in
 function affs_truncate

Thanks for standing up for me Thomas.
If you have any ideas about what is better
please let me known.
Cheers Nick

On Fri, Jun 20, 2014 at 7:59 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Fri, 20 Jun 2014, Nick Krause wrote:
>
>> Ok that's fine I would return as if it's a NULL the other parts of the
>> function can't continue.
>> Nick
>>
>> On Thu, Jun 19, 2014 at 1:21 AM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
>> > On Wed, Jun 18, 2014 at 06:08:05PM -0400, Nicholas Krause wrote:
>> >> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
>> >> ---
>> >>  fs/affs/file.c | 2 ++
>> >>  1 file changed, 2 insertions(+)
>> >>
>> >> diff --git a/fs/affs/file.c b/fs/affs/file.c
>> >> index a7fe57d..f26482d 100644
>> >> --- a/fs/affs/file.c
>> >> +++ b/fs/affs/file.c
>> >> @@ -923,6 +923,8 @@ affs_truncate(struct inode *inode)
>> >>
>> >>       while (ext_key) {
>> >>               ext_bh = affs_bread(sb, ext_key);
>> >> +             if (!ext_bh)
>> >> +                     return;
>> >
>> > The problem is that we don't know if we should return here or break
>> > here.  If you don't understand the code, then it's best to just leave it
>> > alone.
>
> Dan, what kind of attitude is that?
>
> Nick certainly found an issue where a possible NULL return from
> affs_bread() can cause havoc.
>
> Do YOU understand that code?
>
> If yes, you better explain, WHY Nicks finding is a false positive
> instead of just telling him off in a very inpolite way.
>
> If not, you better refrain from telling a reporter that he does not
> understand the code and should stay away.
>
> You clearly stated that you do not understand it either:
>
>> > The problem is that we don't know if we should return here or break
>> > here.
>
> The problem here is that proceeding with a known NULL pointer is wrong
> to begin with. It does not matter at all whether break or return is
> the proper thing to do. What matters is that proceeding with a NULL
> pointer is wrong to begin with, no matter what.
>
> So either explain why this is a non issue and the NULL pointer return
> cannot happen or shut up and try to find a proper solution for that
> "return" vs. "break" issue.
>
> Thanks,
>
>         tglx
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