In dkl_phy_set_hip_idx(), we may try to shift a value negatively,
whose behavior is undefined. This can happen because we define
TC_PORT_NONE to -1, so theoretically tc_port could be -1. We will
then use tc_port to shift to the correct address of the specified
port, but if it's negative, anything can happen.
If this happens or tc_port exceeds I915_MAX_TC_PORTS, it's safer to
return with a warning than risk an invalid write.
Signed-off-by: Luca Coelho <luciano.coe...@intel.com>
---
drivers/gpu/drm/i915/display/intel_dkl_phy.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dkl_phy.c
b/drivers/gpu/drm/i915/display/intel_dkl_phy.c
index dad7192132ad..35e919eae369 100644
--- a/drivers/gpu/drm/i915/display/intel_dkl_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_dkl_phy.c
@@ -25,7 +25,9 @@ dkl_phy_set_hip_idx(struct intel_display *display, struct
intel_dkl_phy_reg reg)
{
enum tc_port tc_port = DKL_REG_TC_PORT(reg);
- drm_WARN_ON(display->drm, tc_port < TC_PORT_1 || tc_port >=
I915_MAX_TC_PORTS);
+ if (drm_WARN_ON(display->drm,
+ tc_port < TC_PORT_1 || tc_port >= I915_MAX_TC_PORTS))
+ return;
intel_de_write(display,
HIP_INDEX_REG(tc_port),
--
2.47.2
