On Wed, 05 Mar 2025, Wentao Liang vulab@iscas.ac.cn wrote:

The return values of `drm_edid_dup()` and `drm_edid_read_ddc()` must be checked in `tegra_output_connector_get_modes()` to prevent NULL pointer dereferences. If either function fails, the function should immediately return 0, indicating that no display modes can be retrieved.

No. It works as designed, and drm_edid_connector_update() and cec_notifier_set_phys_addr() *must* be called with NULL drm_edid in case of failure.

A proper implementation can be found in `vidi_get_modes()`, where the return values are carefully validated, and the function returns 0 upon failure.

That case is slightly different, as it doesn't actually access the display at that point, but it wouldn't be wrong to skip the early !drm_edid check there too.

Fixes: 98365ca74cbf ("drm/tegra: convert to struct drm_edid")

When you claim to fix a commit, it's encouraged to Cc: the author and possibly reviewers of said commit.

BR, Jani.

Cc: stable@vger.kernel.org # 6.12+ Signed-off-by: Wentao Liang vulab@iscas.ac.cn

---

drivers/gpu/drm/tegra/output.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c index 49e4f63a5550..360c4f83a4f8 100644 --- a/drivers/gpu/drm/tegra/output.c +++ b/drivers/gpu/drm/tegra/output.c @@ -39,6 +39,9 @@ int tegra_output_connector_get_modes(struct drm_connector *connector) else if (output->ddc) drm_edid = drm_edid_read_ddc(connector, output->ddc);

• if (!drm_edid)

• return 0;
  

• drm_edid_connector_update(connector, drm_edid); cec_notifier_set_phys_addr(output->cec, connector->display_info.source_physical_address);