[PATCH v3] drm/client: fix null pointer dereference in drm_client_modeset_probe

Ma Ke
2024-07-24T09:45:34Z

In drm_client_modeset_probe(), the return value of drm_mode_duplicate() is
assigned to modeset->mode, which will lead to a possible NULL pointer
dereference on failure of drm_mode_duplicate(). Add a check to avoid npd.

Cc: stable@vger.kernel.org
Fixes: cf13909aee05 ("drm/fb-helper: Move out modeset config code")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v3:
- modified patch as suggestions, returned error directly when failing to
get modeset->mode.
Changes in v2:
- added the recipient's email address, due to the prolonged absence of a
response from the recipients.
- added Cc stable.
---
drivers/gpu/drm/drm_client_modeset.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index 31af5cf37a09..750b8dce0f90 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -880,6 +880,9 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,

kfree(modeset->mode);
modeset->mode = drm_mode_duplicate(dev, mode);
+ if (!modeset->mode)
+ return 0;
+
drm_connector_get(connector);
modeset->connectors[modeset->num_connectors++] = connector;
modeset->x = offset->x;
--
2.25.1