Re: [Intel-gfx] [PATCH] drm/i915: zero fill vma name buffer

On 15/09/2021 20:23, Tim Gardner wrote:

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);

GCC is supposed to catch any problems here as you say in the commit message.

But to fix I suggest a single line change to strlcpy(c->name, name, sizeof(c->name)) which always null terminates as bonus.

Probably same in i915_vma_coredump_create() which with strncpy would have a theoretical chance of attempting to copy over a non-null-terminated string.

Regards,

Tvrtko

c->vma = vma; /* reference held while active */

c->next = next;