linux-kernel - Re: [PATCH] drm: remove redundant code form drm_ioc32.c

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Message-ID: <87lhezugip.fsf@intel.com>
Date:	Thu, 02 Jul 2015 11:10:06 +0300
From:	Jani Nikula <jani.nikula@...ux.intel.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	airlied@...ux.ie, dri-devel@...ts.freedesktop.org
Cc:	open list <linux-kernel@...r.kernel.org>,
	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: Re: [PATCH] drm: remove redundant code form drm_ioc32.c

On Wed, 01 Jul 2015, Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:
> The compat ioctl handler ends up calling access_ok() twice: first
> indirectly inside compat_alloc_user_space() and then after returning
> from that function. This patch fixes issue.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
>  drivers/gpu/drm/drm_ioc32.c | 55 +++++++++++++++++++++------------------------
>  1 file changed, 26 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
> index aa8bbb4..77b63e7 100644
> --- a/drivers/gpu/drm/drm_ioc32.c
> +++ b/drivers/gpu/drm/drm_ioc32.c
> @@ -93,7 +93,7 @@ static int compat_drm_version(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	version = compat_alloc_user_space(sizeof(*version));
> -	if (!access_ok(VERIFY_WRITE, version, sizeof(*version)))
> +	if (!version)
>  		return -EFAULT;
>  	if (__put_user(v32.name_len, &version->name_len)
>  	    || __put_user((void __user *)(unsigned long)v32.name,
> @@ -140,7 +140,7 @@ static int compat_drm_getunique(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	u = compat_alloc_user_space(sizeof(*u));
> -	if (!access_ok(VERIFY_WRITE, u, sizeof(*u)))
> +	if (!u)
>  		return -EFAULT;
>  	if (__put_user(uq32.unique_len, &u->unique_len)
>  	    || __put_user((void __user *)(unsigned long)uq32.unique,
> @@ -168,7 +168,7 @@ static int compat_drm_setunique(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	u = compat_alloc_user_space(sizeof(*u));
> -	if (!access_ok(VERIFY_WRITE, u, sizeof(*u)))
> +	if (!u)
>  		return -EFAULT;
>  	if (__put_user(uq32.unique_len, &u->unique_len)
>  	    || __put_user((void __user *)(unsigned long)uq32.unique,
> @@ -200,7 +200,7 @@ static int compat_drm_getmap(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	map = compat_alloc_user_space(sizeof(*map));
> -	if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
> +	if (!map)
>  		return -EFAULT;
>  	if (__put_user(idx, &map->offset))
>  		return -EFAULT;
> @@ -237,7 +237,7 @@ static int compat_drm_addmap(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	map = compat_alloc_user_space(sizeof(*map));
> -	if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
> +	if (!map)
>  		return -EFAULT;
>  	if (__put_user(m32.offset, &map->offset)
>  	    || __put_user(m32.size, &map->size)
> @@ -277,7 +277,7 @@ static int compat_drm_rmmap(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	map = compat_alloc_user_space(sizeof(*map));
> -	if (!access_ok(VERIFY_WRITE, map, sizeof(*map)))
> +	if (!map)
>  		return -EFAULT;
>  	if (__put_user((void *)(unsigned long)handle, &map->handle))
>  		return -EFAULT;
> @@ -306,7 +306,7 @@ static int compat_drm_getclient(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	client = compat_alloc_user_space(sizeof(*client));
> -	if (!access_ok(VERIFY_WRITE, client, sizeof(*client)))
> +	if (!client)
>  		return -EFAULT;
>  	if (__put_user(idx, &client->idx))
>  		return -EFAULT;
> @@ -345,7 +345,7 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
>  	int i, err;
>  
>  	stats = compat_alloc_user_space(sizeof(*stats));
> -	if (!access_ok(VERIFY_WRITE, stats, sizeof(*stats)))
> +	if (!stats)
>  		return -EFAULT;
>  
>  	err = drm_ioctl(file, DRM_IOCTL_GET_STATS, (unsigned long)stats);
> @@ -382,8 +382,7 @@ static int compat_drm_addbufs(struct file *file, unsigned int cmd,
>  	unsigned long agp_start;
>  
>  	buf = compat_alloc_user_space(sizeof(*buf));
> -	if (!access_ok(VERIFY_WRITE, buf, sizeof(*buf))
> -	    || !access_ok(VERIFY_WRITE, argp, sizeof(*argp)))
> +	if (!buf || !argp)

The risks of touching old code... who does access_ok on argp now? That
doesn't come from compat_alloc_user_space.

Same pattern repeated below a few times.

BR,
Jani.

>  		return -EFAULT;
>  
>  	if (__copy_in_user(buf, argp, offsetof(drm_buf_desc32_t, agp_start))
> @@ -414,7 +413,7 @@ static int compat_drm_markbufs(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	buf = compat_alloc_user_space(sizeof(*buf));
> -	if (!access_ok(VERIFY_WRITE, buf, sizeof(*buf)))
> +	if (!buf)
>  		return -EFAULT;
>  
>  	if (__put_user(b32.size, &buf->size)
> @@ -455,7 +454,7 @@ static int compat_drm_infobufs(struct file *file, unsigned int cmd,
>  
>  	nbytes = sizeof(*request) + count * sizeof(struct drm_buf_desc);
>  	request = compat_alloc_user_space(nbytes);
> -	if (!access_ok(VERIFY_WRITE, request, nbytes))
> +	if (!request)
>  		return -EFAULT;
>  	list = (struct drm_buf_desc *) (request + 1);
>  
> @@ -516,7 +515,7 @@ static int compat_drm_mapbufs(struct file *file, unsigned int cmd,
>  		return -EINVAL;
>  	nbytes = sizeof(*request) + count * sizeof(struct drm_buf_pub);
>  	request = compat_alloc_user_space(nbytes);
> -	if (!access_ok(VERIFY_WRITE, request, nbytes))
> +	if (!request)
>  		return -EFAULT;
>  	list = (struct drm_buf_pub *) (request + 1);
>  
> @@ -563,7 +562,7 @@ static int compat_drm_freebufs(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
> +	if (!request)
>  		return -EFAULT;
>  	if (__put_user(req32.count, &request->count)
>  	    || __put_user((int __user *)(unsigned long)req32.list,
> @@ -589,7 +588,7 @@ static int compat_drm_setsareactx(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
> +	if (!request)
>  		return -EFAULT;
>  	if (__put_user(req32.ctx_id, &request->ctx_id)
>  	    || __put_user((void *)(unsigned long)req32.handle,
> @@ -613,7 +612,7 @@ static int compat_drm_getsareactx(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request)))
> +	if (!request)
>  		return -EFAULT;
>  	if (__put_user(ctx_id, &request->ctx_id))
>  		return -EFAULT;
> @@ -646,7 +645,7 @@ static int compat_drm_resctx(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	res = compat_alloc_user_space(sizeof(*res));
> -	if (!access_ok(VERIFY_WRITE, res, sizeof(*res)))
> +	if (!res)
>  		return -EFAULT;
>  	if (__put_user(res32.count, &res->count)
>  	    || __put_user((struct drm_ctx __user *) (unsigned long)res32.contexts,
> @@ -689,7 +688,7 @@ static int compat_drm_dma(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	d = compat_alloc_user_space(sizeof(*d));
> -	if (!access_ok(VERIFY_WRITE, d, sizeof(*d)))
> +	if (!d)
>  		return -EFAULT;
>  
>  	if (__put_user(d32.context, &d->context)
> @@ -764,7 +763,7 @@ static int compat_drm_agp_info(struct file *file, unsigned int cmd,
>  	int err;
>  
>  	info = compat_alloc_user_space(sizeof(*info));
> -	if (!access_ok(VERIFY_WRITE, info, sizeof(*info)))
> +	if (!info)
>  		return -EFAULT;
>  
>  	err = drm_ioctl(file, DRM_IOCTL_AGP_INFO, (unsigned long)info);
> @@ -807,7 +806,7 @@ static int compat_drm_agp_alloc(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> +	if (!request
>  	    || __put_user(req32.size, &request->size)
>  	    || __put_user(req32.type, &request->type))
>  		return -EFAULT;
> @@ -834,7 +833,7 @@ static int compat_drm_agp_free(struct file *file, unsigned int cmd,
>  	u32 handle;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> +	if (!request
>  	    || get_user(handle, &argp->handle)
>  	    || __put_user(handle, &request->handle))
>  		return -EFAULT;
> @@ -858,7 +857,7 @@ static int compat_drm_agp_bind(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> +	if (!request
>  	    || __put_user(req32.handle, &request->handle)
>  	    || __put_user(req32.offset, &request->offset))
>  		return -EFAULT;
> @@ -874,7 +873,7 @@ static int compat_drm_agp_unbind(struct file *file, unsigned int cmd,
>  	u32 handle;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> +	if (!request
>  	    || get_user(handle, &argp->handle)
>  	    || __put_user(handle, &request->handle))
>  		return -EFAULT;
> @@ -897,8 +896,7 @@ static int compat_drm_sg_alloc(struct file *file, unsigned int cmd,
>  	unsigned long x;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> -	    || !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
> +	if (!request || !argp
>  	    || __get_user(x, &argp->size)
>  	    || __put_user(x, &request->size))
>  		return -EFAULT;
> @@ -923,8 +921,7 @@ static int compat_drm_sg_free(struct file *file, unsigned int cmd,
>  	unsigned long x;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> -	    || !access_ok(VERIFY_WRITE, argp, sizeof(*argp))
> +	if (!request || !argp
>  	    || __get_user(x, &argp->handle)
>  	    || __put_user(x << PAGE_SHIFT, &request->handle))
>  		return -EFAULT;
> @@ -952,7 +949,7 @@ static int compat_drm_update_draw(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request)) ||
> +	if (!request ||
>  	    __put_user(update32.handle, &request->handle) ||
>  	    __put_user(update32.type, &request->type) ||
>  	    __put_user(update32.num, &request->num) ||
> @@ -994,7 +991,7 @@ static int compat_drm_wait_vblank(struct file *file, unsigned int cmd,
>  		return -EFAULT;
>  
>  	request = compat_alloc_user_space(sizeof(*request));
> -	if (!access_ok(VERIFY_WRITE, request, sizeof(*request))
> +	if (!request
>  	    || __put_user(req32.request.type, &request->request.type)
>  	    || __put_user(req32.request.sequence, &request->request.sequence)
>  	    || __put_user(req32.request.signal, &request->request.signal))
> -- 
> 2.1.4
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Jani Nikula, Intel Open Source Technology Center
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