[PATCH 6.1 212/473] drm: bridge: cdns-mhdp8546: Fix possible null pointer dereference

Greg Kroah-Hartman
2024-06-06T14:15:30Z

From: Aleksandr Mishin <amishin@t-argos.ru>

[ 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>
---
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 31442a9225029..1b7c14d7c5ee3 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2042,6 +2042,9 @@ 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);
--
2.43.0