drm/msm/adreno: Remove VLA usage

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 <[email protected]>

---
 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(-)

Quoted 11 lines · 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 <[email protected]>

---
 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.

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 <[email protected]>

---
 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(-)

drivers/gpu/drm/msm/adreno/a5xx_gpu.c +5 -2

index d39400e5bc42..f5f76f8151f9 100644
@@ -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;

drivers/gpu/drm/msm/adreno/adreno_gpu.c +19 -9

index bcbf9f2a29f9..bfaafdfc7eb2 100644
@@ -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)

Signature · 6 lines

2.17.1


-- 
Kees Cook
Pixel Security

Quoted 5 lines · 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

Thanks for doing this.

Acked-by Jordan Crouse <[email protected]>

Quoted 7 lines · Jordan Crouse

Quoted 5 lines · 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

Quoted 3 lines

Thanks for doing this.

Acked-by Jordan Crouse <[email protected]>

Hi Rob,

Is this something you can take via your tree?