[PATCH] drm/msm/adreno: Remove VLA usage

[PATCH] drm/msm/adreno: Remove VLA usage

[Kees Cook]

In the quest to remove all stack VLA usage from the kernel[1], this
switches to using a kasprintf()ed buffer. Return paths are updated
to free the allocation.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/gpu/drm/msm/adreno/a5xx_gpu.c   |  7 +++++--
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 28 +++++++++++++++++--------
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
index d39400e5bc42..f5f76f8151f9 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
@@ -11,6 +11,7 @@
  *
  */
 
+#include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/cpumask.h>
 #include <linux/qcom_scm.h>
@@ -19,6 +20,7 @@
 #include <linux/soc/qcom/mdt_loader.h>
 #include <linux/pm_opp.h>
 #include <linux/nvmem-consumer.h>
+#include <linux/slab.h>
 #include "msm_gem.h"
 #include "msm_mmu.h"
 #include "a5xx_gpu.h"
@@ -91,12 +93,13 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname)
 		ret = qcom_mdt_load(dev, fw, fwname, GPU_PAS_ID,
 				mem_region, mem_phys, mem_size, NULL);
 	} else {
-		char newname[strlen("qcom/") + strlen(fwname) + 1];
+		char *newname;
 
-		sprintf(newname, "qcom/%s", fwname);
+		newname = kasprintf(GFP_KERNEL, "qcom/%s", fwname);
 
 		ret = qcom_mdt_load(dev, fw, newname, GPU_PAS_ID,
 				mem_region, mem_phys, mem_size, NULL);
+		kfree(newname);
 	}
 	if (ret)
 		goto out;
diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index bcbf9f2a29f9..bfaafdfc7eb2 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -17,7 +17,9 @@
  * this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/kernel.h>
 #include <linux/pm_opp.h>
+#include <linux/slab.h>
 #include "adreno_gpu.h"
 #include "msm_gem.h"
 #include "msm_mmu.h"
@@ -70,10 +72,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
 {
 	struct drm_device *drm = adreno_gpu->base.dev;
 	const struct firmware *fw = NULL;
-	char newname[strlen("qcom/") + strlen(fwname) + 1];
+	char *newname;
 	int ret;
 
-	sprintf(newname, "qcom/%s", fwname);
+	newname = kasprintf(GFP_KERNEL, "qcom/%s", fwname);
+	if (!newname)
+		return ERR_PTR(-ENOMEM);
 
 	/*
 	 * Try first to load from qcom/$fwfile using a direct load (to avoid
@@ -87,11 +91,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
 			dev_info(drm->dev, "loaded %s from new location\n",
 				newname);
 			adreno_gpu->fwloc = FW_LOCATION_NEW;
-			return fw;
+			goto out;
 		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
 			dev_err(drm->dev, "failed to load %s: %d\n",
 				newname, ret);
-			return ERR_PTR(ret);
+			fw = ERR_PTR(ret);
+			goto out;
 		}
 	}
 
@@ -106,11 +111,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
 			dev_info(drm->dev, "loaded %s from legacy location\n",
 				newname);
 			adreno_gpu->fwloc = FW_LOCATION_LEGACY;
-			return fw;
+			goto out;
 		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
 			dev_err(drm->dev, "failed to load %s: %d\n",
 				fwname, ret);
-			return ERR_PTR(ret);
+			fw = ERR_PTR(ret);
+			goto out;
 		}
 	}
 
@@ -126,16 +132,20 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
 			dev_info(drm->dev, "loaded %s with helper\n",
 				newname);
 			adreno_gpu->fwloc = FW_LOCATION_HELPER;
-			return fw;
+			goto out;
 		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
 			dev_err(drm->dev, "failed to load %s: %d\n",
 				newname, ret);
-			return ERR_PTR(ret);
+			fw = ERR_PTR(ret);
+			goto out;
 		}
 	}
 
 	dev_err(drm->dev, "failed to load %s\n", fwname);
-	return ERR_PTR(-ENOENT);
+	fw = ERR_PTR(-ENOENT);
+out:
+	kfree(newname);
+	return fw;
 }
 
 static int adreno_load_fw(struct adreno_gpu *adreno_gpu)
-- 
2.17.1


-- 
Kees Cook
Pixel Security

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[Arnd Bergmann]

On Fri, Jun 29, 2018 at 8:48 PM, Kees Cook <keescook@chromium.org> wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> switches to using a kasprintf()ed buffer. Return paths are updated
> to free the allocation.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c   |  7 +++++--
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 28 +++++++++++++++++--------
>  2 files changed, 24 insertions(+), 11 deletions(-)

This seems fine, though using a fixed-length string is probably just
as well here,
given that the 'fwname' variable is always set to the constant string
"a530_zap.mdt"
at the moment, which is not very long.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

       Arnd

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[Jordan Crouse]

On Fri, Jun 29, 2018 at 10:47:31PM +0200, Arnd Bergmann wrote:
> On Fri, Jun 29, 2018 at 8:48 PM, Kees Cook <keescook@chromium.org> wrote:
> > In the quest to remove all stack VLA usage from the kernel[1], this
> > switches to using a kasprintf()ed buffer. Return paths are updated
> > to free the allocation.
> >
> > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
> >
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> >  drivers/gpu/drm/msm/adreno/a5xx_gpu.c   |  7 +++++--
> >  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 28 +++++++++++++++++--------
> >  2 files changed, 24 insertions(+), 11 deletions(-)
> 
> This seems fine, though using a fixed-length string is probably just
> as well here,
> given that the 'fwname' variable is always set to the constant string
> "a530_zap.mdt"
> at the moment, which is not very long.

We could make it fixed but since this code is only called once this
feels safer.

Jordan

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[Jordan Crouse]

On Fri, Jun 29, 2018 at 11:48:18AM -0700, Kees Cook wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> switches to using a kasprintf()ed buffer. Return paths are updated
> to free the allocation.
> 
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Thanks for doing this.

Acked-by: Jordan Crouse <jcrouse@codeaurora.org>

> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c   |  7 +++++--
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 28 +++++++++++++++++--------
>  2 files changed, 24 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index d39400e5bc42..f5f76f8151f9 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -11,6 +11,7 @@
>   *
>   */
>  
> +#include <linux/kernel.h>
>  #include <linux/types.h>
>  #include <linux/cpumask.h>
>  #include <linux/qcom_scm.h>
> @@ -19,6 +20,7 @@
>  #include <linux/soc/qcom/mdt_loader.h>
>  #include <linux/pm_opp.h>
>  #include <linux/nvmem-consumer.h>
> +#include <linux/slab.h>
>  #include "msm_gem.h"
>  #include "msm_mmu.h"
>  #include "a5xx_gpu.h"
> @@ -91,12 +93,13 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname)
>  		ret = qcom_mdt_load(dev, fw, fwname, GPU_PAS_ID,
>  				mem_region, mem_phys, mem_size, NULL);
>  	} else {
> -		char newname[strlen("qcom/") + strlen(fwname) + 1];
> +		char *newname;
>  
> -		sprintf(newname, "qcom/%s", fwname);
> +		newname = kasprintf(GFP_KERNEL, "qcom/%s", fwname);
>  
>  		ret = qcom_mdt_load(dev, fw, newname, GPU_PAS_ID,
>  				mem_region, mem_phys, mem_size, NULL);
> +		kfree(newname);
>  	}
>  	if (ret)
>  		goto out;
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index bcbf9f2a29f9..bfaafdfc7eb2 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -17,7 +17,9 @@
>   * this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/kernel.h>
>  #include <linux/pm_opp.h>
> +#include <linux/slab.h>
>  #include "adreno_gpu.h"
>  #include "msm_gem.h"
>  #include "msm_mmu.h"
> @@ -70,10 +72,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
>  {
>  	struct drm_device *drm = adreno_gpu->base.dev;
>  	const struct firmware *fw = NULL;
> -	char newname[strlen("qcom/") + strlen(fwname) + 1];
> +	char *newname;
>  	int ret;
>  
> -	sprintf(newname, "qcom/%s", fwname);
> +	newname = kasprintf(GFP_KERNEL, "qcom/%s", fwname);
> +	if (!newname)
> +		return ERR_PTR(-ENOMEM);
>  
>  	/*
>  	 * Try first to load from qcom/$fwfile using a direct load (to avoid
> @@ -87,11 +91,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
>  			dev_info(drm->dev, "loaded %s from new location\n",
>  				newname);
>  			adreno_gpu->fwloc = FW_LOCATION_NEW;
> -			return fw;
> +			goto out;
>  		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
>  			dev_err(drm->dev, "failed to load %s: %d\n",
>  				newname, ret);
> -			return ERR_PTR(ret);
> +			fw = ERR_PTR(ret);
> +			goto out;
>  		}
>  	}
>  
> @@ -106,11 +111,12 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
>  			dev_info(drm->dev, "loaded %s from legacy location\n",
>  				newname);
>  			adreno_gpu->fwloc = FW_LOCATION_LEGACY;
> -			return fw;
> +			goto out;
>  		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
>  			dev_err(drm->dev, "failed to load %s: %d\n",
>  				fwname, ret);
> -			return ERR_PTR(ret);
> +			fw = ERR_PTR(ret);
> +			goto out;
>  		}
>  	}
>  
> @@ -126,16 +132,20 @@ adreno_request_fw(struct adreno_gpu *adreno_gpu, const char *fwname)
>  			dev_info(drm->dev, "loaded %s with helper\n",
>  				newname);
>  			adreno_gpu->fwloc = FW_LOCATION_HELPER;
> -			return fw;
> +			goto out;
>  		} else if (adreno_gpu->fwloc != FW_LOCATION_UNKNOWN) {
>  			dev_err(drm->dev, "failed to load %s: %d\n",
>  				newname, ret);
> -			return ERR_PTR(ret);
> +			fw = ERR_PTR(ret);
> +			goto out;
>  		}
>  	}
>  
>  	dev_err(drm->dev, "failed to load %s\n", fwname);
> -	return ERR_PTR(-ENOENT);
> +	fw = ERR_PTR(-ENOENT);
> +out:
> +	kfree(newname);
> +	return fw;
>  }
>  
>  static int adreno_load_fw(struct adreno_gpu *adreno_gpu)
> -- 
> 2.17.1
> 
> 
> -- 
> Kees Cook
> Pixel Security

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[Kees Cook]

On Fri, Jun 29, 2018 at 2:20 PM, Jordan Crouse <jcrouse@codeaurora.org> wrote:
> On Fri, Jun 29, 2018 at 11:48:18AM -0700, Kees Cook wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> switches to using a kasprintf()ed buffer. Return paths are updated
>> to free the allocation.
>>
>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Thanks for doing this.
>
> Acked-by: Jordan Crouse <jcrouse@codeaurora.org>

Hi Rob,

Is this something you can take via your tree?

Thanks,

-Kees

-- 
Kees Cook
Pixel Security

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[Rob Clark]

On Thu, Aug 2, 2018 at 7:24 PM, Kees Cook <keescook@chromium.org> wrote:
> On Fri, Jun 29, 2018 at 2:20 PM, Jordan Crouse <jcrouse@codeaurora.org> wrote:
>> On Fri, Jun 29, 2018 at 11:48:18AM -0700, Kees Cook wrote:
>>> In the quest to remove all stack VLA usage from the kernel[1], this
>>> switches to using a kasprintf()ed buffer. Return paths are updated
>>> to free the allocation.
>>>
>>> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>>
>> Thanks for doing this.
>>
>> Acked-by: Jordan Crouse <jcrouse@codeaurora.org>
>
> Hi Rob,
>
> Is this something you can take via your tree?
>

Oh, sorry, I missed this one, I'll pick it up shortly..

BR,
-R

Re: [PATCH] drm/msm/adreno: Remove VLA usage

[SF Markus Elfring]

> @@ -91,12 +93,13 @@  static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname)
>  		ret = qcom_mdt_load(dev, fw, fwname, GPU_PAS_ID,
>  				mem_region, mem_phys, mem_size, NULL);
>  	} else {
> -		char newname[strlen("qcom/") + strlen(fwname) + 1];
> +		char *newname;
> 
> -		sprintf(newname, "qcom/%s", fwname);
> +		newname = kasprintf(GFP_KERNEL, "qcom/%s", fwname);
> 
>  		ret = qcom_mdt_load(dev, fw, newname, GPU_PAS_ID,
>  				mem_region, mem_phys, mem_size, NULL);

I have taken another look also at this update suggestion.
Now I wonder why the return value is not checked for the added name construction
in the way as it is specified for the function “adreno_request_fw”.
Will another condition check make sense at this place?

Regards,
Markus