All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jani Nikula <jani.nikula@linux.intel.com>
To: Daniel Vetter <daniel@ffwll.ch>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 1/1] drm: avoid exposing kernel stack in compat_drm_getstats
Date: Mon, 22 Aug 2016 11:29:07 +0300	[thread overview]
Message-ID: <87fupxurzg.fsf@intel.com> (raw)
In-Reply-To: <20160822072718.GC6232@phenom.ffwll.local>

On Mon, 22 Aug 2016, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Sun, Aug 21, 2016 at 07:56:19PM +0200, Heinrich Schuchardt wrote:
>> The C standard does not specify the size of the integer used
>> to store an enum. Hence in structure drm_stats32_t alignment
>> bytes may exist.
>> 
>> To avoid exposing bytes from the kernel stack it is
>> necessary to initialize variable s32 completely.
>> 
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
>
> Applied to drm-misc, thanks.
> -Daniel
>
>> ---
>>  drivers/gpu/drm/drm_ioc32.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
>> index 57676f8..32a489b 100644
>> --- a/drivers/gpu/drm/drm_ioc32.c
>> +++ b/drivers/gpu/drm/drm_ioc32.c
>> @@ -346,6 +346,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
>>  	struct drm_stats __user *stats;
>>  	int i, err;
>>  
>> +	memset(&s32, 0, sizeof(drm_stats32_t));

For future reference,

	memset(&s32, 0, sizeof(s32));

is the better approach, avoiding problems if the type of s32 ever
changes.

BR,
Jani.


>>  	stats = compat_alloc_user_space(sizeof(*stats));
>>  	if (!stats)
>>  		return -EFAULT;
>> -- 
>> 2.1.4
>> 
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Jani Nikula, Intel Open Source Technology Center
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: Jani Nikula <jani.nikula@linux.intel.com>
To: Daniel Vetter <daniel@ffwll.ch>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 1/1] drm: avoid exposing kernel stack in compat_drm_getstats
Date: Mon, 22 Aug 2016 11:29:07 +0300	[thread overview]
Message-ID: <87fupxurzg.fsf@intel.com> (raw)
In-Reply-To: <20160822072718.GC6232@phenom.ffwll.local>

On Mon, 22 Aug 2016, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Sun, Aug 21, 2016 at 07:56:19PM +0200, Heinrich Schuchardt wrote:
>> The C standard does not specify the size of the integer used
>> to store an enum. Hence in structure drm_stats32_t alignment
>> bytes may exist.
>> 
>> To avoid exposing bytes from the kernel stack it is
>> necessary to initialize variable s32 completely.
>> 
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
>
> Applied to drm-misc, thanks.
> -Daniel
>
>> ---
>>  drivers/gpu/drm/drm_ioc32.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
>> index 57676f8..32a489b 100644
>> --- a/drivers/gpu/drm/drm_ioc32.c
>> +++ b/drivers/gpu/drm/drm_ioc32.c
>> @@ -346,6 +346,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
>>  	struct drm_stats __user *stats;
>>  	int i, err;
>>  
>> +	memset(&s32, 0, sizeof(drm_stats32_t));

For future reference,

	memset(&s32, 0, sizeof(s32));

is the better approach, avoiding problems if the type of s32 ever
changes.

BR,
Jani.


>>  	stats = compat_alloc_user_space(sizeof(*stats));
>>  	if (!stats)
>>  		return -EFAULT;
>> -- 
>> 2.1.4
>> 
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Jani Nikula, Intel Open Source Technology Center

  reply	other threads:[~2016-08-22  8:29 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-21 17:56 [PATCH 1/1] drm: avoid exposing kernel stack in compat_drm_getstats Heinrich Schuchardt
2016-08-22  7:27 ` Daniel Vetter
2016-08-22  8:29   ` Jani Nikula [this message]
2016-08-22  8:29     ` Jani Nikula

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=87fupxurzg.fsf@intel.com \
    --to=jani.nikula@linux.intel.com \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=xypron.glpk@gmx.de \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.