From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: benh@kernel.crashing.org, paulus@samba.org,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
kernel-janitors@vger.kernel.org
Subject: Re: [PATCH v2] powerpc/mpc5xxx: Avoid dereferencing potentially freed memory
Date: Fri, 16 Oct 2015 22:05:55 +0200 [thread overview]
Message-ID: <562158A3.90000@wanadoo.fr> (raw)
In-Reply-To: <1444988979.12954.1.camel@ellerman.id.au>
Le 16/10/2015 11:49, Michael Ellerman a écrit :
> On Fri, 2015-10-16 at 08:20 +0200, Christophe JAILLET wrote:
>> Le 15/10/2015 08:36, Michael Ellerman a écrit :
>>> On Thu, 2015-10-15 at 07:56 +0200, Christophe JAILLET wrote:
>>>> Use 'of_property_read_u32()' instead of
>>>> 'of_get_property()'+pointer
>>>> dereference in order to avoid access to potentially freed memory.
>>>>
>>>> Use 'of_get_next_parent()' to simplify the while() loop and avoid
>>>> the
>>>> need of a temp variable.
>>>>
>>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>>>> ---
>>>> v2: Use of_property_read_u32 instead of of_get_property+pointer
>>>> dereference
>>>> *** Untested ***
>>> Thanks.
>>>
>>> Can someone with an mpc5xxx test this?
>> Hi,
>> I don't think it is an issue, but while looking at another similar
>> patch, I noticed that the proposed patch adds a call to
>> be32_to_cpup()
>> (within of_property_read_u32).
>> Apparently, powerPC is a BE architecture, so this call should be a no
>> -op.
>>
>> Just wanted to point it out, in case of.
> Hi Christoph,
>
> I'm not sure I follow.
>
> The device tree is always big endian, but of_property_read_u32() does
> the
> conversion to CPU endian for you already. That is one of the advantages
> of
> using it.
>
> cheers
>
Hi,
sorry if un-clear.
What I mean is that in the patch related
'powerpc/sysdev/mpc5xxx_clocks.c', there was no call to 'be32_to_cpup'.
So in the proposed patch, 'of_property_read_u32' adds it.
While in the patch against 'powerpc/kernel/prom.c', 'be32_to_cpup' was
called explicitly.
So using 'of_property_read_u32' keep the same logic.
Basically the code from 'mpc5xxx_clocks.c' and from 'prom.c' were
written the same way. I found spurious that a call to 'be32_to_cpup' was
done in only one case.
Maybe, it was a missing in 'mpc5xxx_clocks.c'.
I don't know if it can be an issue or not. I just find it 'strange'.
CJ
next prev parent reply other threads:[~2015-10-16 20:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-11 20:27 [PATCH] powerpc/mpc5xxx: Use of_get_next_parent to simplify code Christophe JAILLET
2015-10-11 20:44 ` Julia Lawall
2015-10-12 5:05 ` Christophe JAILLET
2015-10-14 4:00 ` Michael Ellerman
2015-10-15 5:56 ` [PATCH v2] powerpc/mpc5xxx: Avoid dereferencing potentially freed memory Christophe JAILLET
2015-10-15 6:36 ` Michael Ellerman
2015-10-16 6:20 ` Christophe JAILLET
2015-10-16 7:15 ` Gabriel Paubert
2015-10-16 9:49 ` Michael Ellerman
2015-10-16 20:05 ` Christophe JAILLET [this message]
2015-10-19 4:38 ` Michael Ellerman
2015-10-15 11:11 ` powerpc/mpc5xxx: Use of_get_next_parent to simplify code Michael Ellerman
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=562158A3.90000@wanadoo.fr \
--to=christophe.jaillet@wanadoo.fr \
--cc=benh@kernel.crashing.org \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
/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;
as well as URLs for NNTP newsgroup(s).