drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference

[ Upstream commit 935a92a1c400285545198ca2800a4c6c519c650a ]

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>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240408125810.21899-1-amishin@t-argos.ru
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 5530fbf64f1e492459ef7666658bff047c9473c0..c8386311cc70450618fd5e7b7be5729c6fa10afd 100644 (file)
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2040,6 +2040,9 @@ 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);