Applied. Thanks!

Alex

On Thu, Dec 2, 2021 at 11:17 AM Zhou Qingyang zhou1615@umn.edu wrote:

In amdgpu_connector_lcd_native_mode(), the return value of drm_mode_duplicate() is assigned to mode, and there is a dereference of it in amdgpu_connector_lcd_native_mode(), which will lead to a NULL pointer dereference on failure of drm_mode_duplicate().

Fix this bug add a check of mode.

This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug.

Builds with CONFIG_DRM_AMDGPU=m show no new warnings, and our static analyzer no longer warns about this code.

Fixes: d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)") Signed-off-by: Zhou Qingyang zhou1615@umn.edu

---

Changes in v2:

• Fix the similar bug in else clause

drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c index 0de66f59adb8..df1f9b88a53f 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c @@ -387,6 +387,9 @@ amdgpu_connector_lcd_native_mode(struct drm_encoder *encoder) native_mode->vdisplay != 0 && native_mode->clock != 0) { mode = drm_mode_duplicate(dev, native_mode);

•           if (!mode)
  

•                   return NULL;
  

•           mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
            drm_mode_set_name(mode);
  
  

@@ -401,6 +404,9 @@ amdgpu_connector_lcd_native_mode(struct drm_encoder *encoder) * simpler. */ mode = drm_cvt_mode(dev, native_mode->hdisplay, native_mode->vdisplay, 60, true, false, false);

•           if (!mode)
  

•                   return NULL;
  

•           mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
            DRM_DEBUG_KMS("Adding cvt approximation of native panel mode %s\n", mode->name);
    }
  

-- 2.25.1