Re: [Intel-gfx] [PATCH v2] drm/i915: use strscpy() to avoid buffer overrun

[Tvrtko Ursulin]

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.nik...@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Cc: David Airlie <airl...@linux.ie>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-de...@lists.freedesktop.org
Cc: linux-ker...@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gard...@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.ursu...@intel.com>

Regards,

Tvrtko