In cdns_mhdp_atomic_enable(), the return value of drm_mode_duplicate() is
assigned to mhdp_state->current_mode, and there is a dereference of it in
drm_mode_set_name(), which will lead to a NULL pointer dereference on
failure of drm_mode_duplicate().

Fix this bug add a check of mhdp_state->current_mode.

Fixes: fb43aa0acdfd ("drm: bridge: Add support for Cadence MHDP8546 DPI/DP bridge")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
---
 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index e226acc5c15e..8a91ef0ae065 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2059,6 +2059,9 @@ static void cdns_mhdp_atomic_enable(struct drm_bridge *bridge,
 	mhdp_state = to_cdns_mhdp_bridge_state(new_state);
 
 	mhdp_state->current_mode = drm_mode_duplicate(bridge->dev, mode);
+	if (!mhdp_state->current_mode)
+		return;
+
 	drm_mode_set_name(mhdp_state->current_mode);
 
 	dev_dbg(mhdp->dev, "%s: Enabling mode %s\n", __func__, mode->name);
-- 
2.30.2

On Mon, 8 Apr 2024 15:58:10 +0300, Aleksandr Mishin wrote:
> In cdns_mhdp_atomic_enable(), the return value of drm_mode_duplicate() is
> assigned to mhdp_state->current_mode, and there is a dereference of it in
> drm_mode_set_name(), which will lead to a NULL pointer dereference on
> failure of drm_mode_duplicate().
> 
> Fix this bug add a check of mhdp_state->current_mode.
> 
> [...]

Applied, thanks!

[1/1] drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference
      https://cgit.freedesktop.org/drm/drm-misc/commit/?id=935a92a1c400



Rob