From 83482ca3b4fe7312bf3d1f25c7a4e9ff66585eab Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 5 Oct 2017 14:08:26 +0200 Subject: [PATCH] drm/i915: avoid potential uninitialized variable use One of the recent changes introduced a warning about undefined behavior in the sanity checking: drivers/gpu/drm/i915/intel_ddi.c: In function 'intel_ddi_hdmi_level': drivers/gpu/drm/i915/intel_ddi.c:654:6: error: 'n_hdmi_entries' may be used uninitialized in this function [-Werror=maybe-uninitialized] It seems that the new cnl specific get_buf_trans functions can return uninitialized data if the voltage level is set to an unexpected value. This changes the code to always return '1' in that error case, which seems like the safest choice as we use one less than the number as an array index later on. Fixes: cc9cabfdec38 ("drm/i915/cnl: Move voltage check into ddi buf trans functions.") Signed-off-by: Arnd Bergmann [danvet: shut up gcc comment added.] Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20171005120835.437022-1-arnd@arndb.de --- drivers/gpu/drm/i915/intel_ddi.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c index 511aa60..f7c91bb 100644 --- a/drivers/gpu/drm/i915/intel_ddi.c +++ b/drivers/gpu/drm/i915/intel_ddi.c @@ -602,8 +602,10 @@ cnl_get_buf_trans_hdmi(struct drm_i915_private *dev_priv, int *n_entries) } else if (voltage == VOLTAGE_INFO_1_05V) { *n_entries = ARRAY_SIZE(cnl_ddi_translations_hdmi_1_05V); return cnl_ddi_translations_hdmi_1_05V; - } else + } else { + *n_entries = 1; /* shut up gcc */ MISSING_CASE(voltage); + } return NULL; } @@ -621,8 +623,10 @@ cnl_get_buf_trans_dp(struct drm_i915_private *dev_priv, int *n_entries) } else if (voltage == VOLTAGE_INFO_1_05V) { *n_entries = ARRAY_SIZE(cnl_ddi_translations_dp_1_05V); return cnl_ddi_translations_dp_1_05V; - } else + } else { + *n_entries = 1; /* shut up gcc */ MISSING_CASE(voltage); + } return NULL; } @@ -641,8 +645,10 @@ cnl_get_buf_trans_edp(struct drm_i915_private *dev_priv, int *n_entries) } else if (voltage == VOLTAGE_INFO_1_05V) { *n_entries = ARRAY_SIZE(cnl_ddi_translations_edp_1_05V); return cnl_ddi_translations_edp_1_05V; - } else + } else { + *n_entries = 1; /* shut up gcc */ MISSING_CASE(voltage); + } return NULL; } else { return cnl_get_buf_trans_dp(dev_priv, n_entries); -- 2.7.4