Function intel_port_to_tc() returns PORT_TC_NONE on error, which is a negative value -1. In case PORT_TC_NONE is returned, there is an undefined behavior when shifting by a negative number of bits in both DP_PHY_MODE_STATUS_NOT_SAFE and P_PHY_MODE_STATUS_COMPLETED macros.
Fix this by adding sanity checks on intel_port_to_tc return value, before using macros DP_PHY_MODE_STATUS_NOT_SAFE and P_PHY_MODE_STATUS_COMPLETED.
Addresses-Coverity-ID: 1473324 ("Bad bit shift operation") Addresses-Coverity-ID: 1473325 ("Bad bit shift operation") Fixes: 39d1e234e1e1 ("drm/i915/icl: implement the tc/legacy HPD {dis,}connect flows") Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com --- drivers/gpu/drm/i915/intel_dp.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 436c22d..e34b7b1 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4811,6 +4811,11 @@ static bool icl_tc_phy_connect(struct drm_i915_private *dev_priv, dig_port->tc_type != TC_PORT_TYPEC) return true;
+ if (tc_port < 0) { + DRM_DEBUG_KMS("Bad TC port %d\n", tc_port); + return false; + } + val = I915_READ(PORT_TX_DFLEXDPPMS); if (!(val & DP_PHY_MODE_STATUS_COMPLETED(tc_port))) { DRM_DEBUG_KMS("DP PHY for TC port %d not ready\n", tc_port); @@ -4857,6 +4862,10 @@ static void icl_tc_phy_disconnect(struct drm_i915_private *dev_priv, dig_port->tc_type != TC_PORT_TYPEC) return;
+ if (tc_port < 0) { + DRM_DEBUG_KMS("Bad TC port %d\n", tc_port); + return; + } /* * This function may be called many times in a row without an HPD event * in between, so try to avoid the write when we can.
Em Qua, 2018-09-12 às 09:31 -0500, Gustavo A. R. Silva escreveu:
Function intel_port_to_tc() returns PORT_TC_NONE on error, which is a negative value -1. In case PORT_TC_NONE is returned, there is an undefined behavior when shifting by a negative number of bits in both DP_PHY_MODE_STATUS_NOT_SAFE and P_PHY_MODE_STATUS_COMPLETED macros.
Fix this by adding sanity checks on intel_port_to_tc return value, before using macros DP_PHY_MODE_STATUS_NOT_SAFE and P_PHY_MODE_STATUS_COMPLETED.
This was just discussed yesterday in a patch by Rodrigo:
https://patchwork.freedesktop.org/patch/246903/
I would personally prefer his version because it avoids passing -1 to register macros that Coverity doesn't seem to care about, it's a single check and it prints WARN() instead of DRM_DEBUG_KMS().
Although I do prefer your commit message explanation :).
Perhaps I should reconsider my vote to not merge it. Or we could actually go and test what happens when intel_port_to_tc() is broken, fixing all the issues instead of just the ones reported by Coverity.
Anyway, Rodrigo's patch with an improved commit message could receive my R-B tag now.
Addresses-Coverity-ID: 1473324 ("Bad bit shift operation") Addresses-Coverity-ID: 1473325 ("Bad bit shift operation") Fixes: 39d1e234e1e1 ("drm/i915/icl: implement the tc/legacy HPD {dis,}connect flows") Signed-off-by: Gustavo A. R. Silva gustavo@embeddedor.com
drivers/gpu/drm/i915/intel_dp.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 436c22d..e34b7b1 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -4811,6 +4811,11 @@ static bool icl_tc_phy_connect(struct drm_i915_private *dev_priv, dig_port->tc_type != TC_PORT_TYPEC) return true;
- if (tc_port < 0) {
DRM_DEBUG_KMS("Bad TC port %d\n", tc_port);return false;- }
- val = I915_READ(PORT_TX_DFLEXDPPMS); if (!(val & DP_PHY_MODE_STATUS_COMPLETED(tc_port))) { DRM_DEBUG_KMS("DP PHY for TC port %d not ready\n",
tc_port); @@ -4857,6 +4862,10 @@ static void icl_tc_phy_disconnect(struct drm_i915_private *dev_priv, dig_port->tc_type != TC_PORT_TYPEC) return;
- if (tc_port < 0) {
DRM_DEBUG_KMS("Bad TC port %d\n", tc_port);return;- } /*
- This function may be called many times in a row without
an HPD event * in between, so try to avoid the write when we can.
dri-devel@lists.freedesktop.org
-
Gustavo A. R. Silva -
Paulo Zanoni