From: Dan Carpenter <error27@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: kernel-janitors@vger.kernel.org, linux-afs@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch] afs: potential null dereference
Date: Mon, 22 Mar 2010 12:56:26 +0000 [thread overview]
Message-ID: <20100322125626.GM21571@bicker> (raw)
In-Reply-To: <28809.1269259520@redhat.com>
On Mon, Mar 22, 2010 at 12:05:20PM +0000, David Howells wrote:
> Dan Carpenter <error27@gmail.com> wrote:
>
> > It seems clear from the surrounding code that xpermits is allowed to be
> > NULL here.
>
> Interesting. The memcpy() won't oops due to this because if it is given a
> NULL pointer, it will also be given a zero count. I wonder if this means the
> if-statement your patch adds is actually unnecessary...
>
I was concerned about the dereference here:
+ if (xpermits)
+ memcpy(permits->permits, xpermits->permits,
^^^^^^^^^^^^^^^^^
+ count * sizeof(struct afs_permit));
This code has been there for three years, so yeah, you would think if it
were a problem someone would have complained. My theory was "xpermits"
was almost always non-null.
regards,
dan carpenter
> David
WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <error27@gmail.com>
To: David Howells <dhowells@redhat.com>
Cc: kernel-janitors@vger.kernel.org, linux-afs@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch] afs: potential null dereference
Date: Mon, 22 Mar 2010 15:56:26 +0300 [thread overview]
Message-ID: <20100322125626.GM21571@bicker> (raw)
In-Reply-To: <28809.1269259520@redhat.com>
On Mon, Mar 22, 2010 at 12:05:20PM +0000, David Howells wrote:
> Dan Carpenter <error27@gmail.com> wrote:
>
> > It seems clear from the surrounding code that xpermits is allowed to be
> > NULL here.
>
> Interesting. The memcpy() won't oops due to this because if it is given a
> NULL pointer, it will also be given a zero count. I wonder if this means the
> if-statement your patch adds is actually unnecessary...
>
I was concerned about the dereference here:
+ if (xpermits)
+ memcpy(permits->permits, xpermits->permits,
^^^^^^^^^^^^^^^^^
+ count * sizeof(struct afs_permit));
This code has been there for three years, so yeah, you would think if it
were a problem someone would have complained. My theory was "xpermits"
was almost always non-null.
regards,
dan carpenter
> David
next prev parent reply other threads:[~2010-03-22 12:56 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-20 11:19 [patch] afs: potential null dereference Dan Carpenter
2010-03-20 11:19 ` Dan Carpenter
2010-03-22 12:05 ` David Howells
2010-03-22 12:56 ` Dan Carpenter [this message]
2010-03-22 12:56 ` Dan Carpenter
2010-03-22 13:05 ` David Howells
-- strict thread matches above, loose matches on Subject: below --
2010-03-22 13:07 [PATCH] AFS: Potential " David Howells
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