On 9/16/21 4:43 AM, Jani Nikula wrote:

On Thu, 16 Sep 2021, Tvrtko Ursulin tvrtko.ursulin@linux.intel.com wrote:

...

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.

strscpy() is preferred over both strncpy() and strlcpy(). :)

BR, Jani.

Good call. v2 on the way.

rtg

...

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;

On 16/09/2021 13:26, 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 strscpy() which guarantees NULL termination.

Also correct 2 other strcpy() call sites with the same potential for Coverity warnings or overruns.

v2 - Change $SUBJECT from "drm/i915: zero fill vma name buffer" Use strscpy() instead of strncpy(). Its a much simpler change.

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 | 6 +++--- 1 file changed, 3 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..7f246f51959d 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -1015,7 +1015,7 @@ i915_vma_coredump_create(const struct intel_gt *gt, return NULL; }

• strcpy(dst->name, name);

• strscpy(dst->name, name, sizeof(dst->name)); dst->next = NULL;

  dst->gtt_offset = vma->node.start;

@@ -1279,7 +1279,7 @@ static bool record_context(struct i915_gem_context_coredump *e, rcu_read_lock(); task = pid_task(ctx->pid, PIDTYPE_PID); if (task) {

• strcpy(e->comm, task->comm);
  

• strscpy(e->comm, task->comm, sizeof(e->comm));
  

  e->pid = task->pid; } rcu_read_unlock();

@@ -1323,7 +1323,7 @@ capture_vma(struct intel_engine_capture_vma *next, return next; }

• strcpy(c->name, name);

• strscpy(c->name, name, sizeof(c->name)); c->vma = vma; /* reference held while active */

  c->next = next;

Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com

Regards,

Tvrtko