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From:   Tim Gardner <tim.gardner@canonical.com>
To:     linux-kernel@vger.kernel.org
Cc:     tim.gardner@canonical.com,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: [PATCH] drm/i915: zero fill vma name buffer
Date:   Wed, 15 Sep 2021 13:23:18 -0600
Message-Id: <20210915192318.2061-1-tim.gardner@canonical.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In capture_vma() Coverity complains of a possible buffer overrun. Even
though this is a static function where all call sites can be checked,
limiting the copy length could save some future grief.

CID 93300 (#1 of 1): Copy into fixed size buffer (STRING_OVERFLOW)
4. fixed_size_dest: You might overrun the 16-character fixed-size string c->name
   by copying name without checking the length.
5. parameter_as_source: Note: This defect has an elevated risk because the
   source argument is a parameter of the current function.
1326        strcpy(c->name, name);

Fix any possible overflows by using strncpy(). Zero fill the name buffer to
guarantee ASCII string NULL termination.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 9cf6ac575de1..154df174e2d7 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1297,10 +1297,11 @@ static bool record_context(struct i915_gem_context_coredump *e,
 	return simulated;
 }
 
+#define VMA_NAME_LEN 16
 struct intel_engine_capture_vma {
 	struct intel_engine_capture_vma *next;
 	struct i915_vma *vma;
-	char name[16];
+	char name[VMA_NAME_LEN];
 };
 
 static struct intel_engine_capture_vma *
@@ -1314,7 +1315,7 @@ capture_vma(struct intel_engine_capture_vma *next,
 	if (!vma)
 		return next;
 
-	c = kmalloc(sizeof(*c), gfp);
+	c = kzalloc(sizeof(*c), gfp);
 	if (!c)
 		return next;
 
@@ -1323,7 +1324,7 @@ capture_vma(struct intel_engine_capture_vma *next,
 		return next;
 	}
 
-	strcpy(c->name, name);
+	strncpy(c->name, name, VMA_NAME_LEN-1);
 	c->vma = vma; /* reference held while active */
 
 	c->next = next;
-- 
2.33.0