From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751440AbdJEMJE (ORCPT ); Thu, 5 Oct 2017 08:09:04 -0400 Received: from mout.kundenserver.de ([212.227.126.135]:51515 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751239AbdJEMJC (ORCPT ); Thu, 5 Oct 2017 08:09:02 -0400 From: Arnd Bergmann To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie Cc: Arnd Bergmann , =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= , Ander Conselvan de Oliveira , Daniel Vetter , Maarten Lankhorst , Tvrtko Ursulin , Shashank Sharma , Paulo Zanoni , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH] drm/i915: avoid potential uninitialized variable use Date: Thu, 5 Oct 2017 14:08:26 +0200 Message-Id: <20171005120835.437022-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:IGQD19kU3sYz5XeROmYmH4WJha7PaqY+XWQMtM6yne3+j0gji34 syjtJ/Qzlt6GIWKvrATfv1ikG2/MEE521Cvqv0EHsU1J5tAwhG9l+qEk4c1Mb3PVOU2Tnsi UpT6F7oDWz5mtqyzCdM7LYvALPRa5G5NXt20mSN1JCaukyzzZs/YUgXhena0RTqorBoezO5 n01BKrBaaZphJwa+UIMQg== X-UI-Out-Filterresults: notjunk:1;V01:K0:p35m9x/HbOQ=:AHZ0S5xiRPzAgqlRNEC1K9 DeXVnlOaV+tPMPdLty0nhYXkz59ijbwzVU13u+ctmvypE4RIEzxOLPv7w9llzhklX2MHOxzza Dt21rIc8FL7P3VuxNVoseiPc0UBdviv6JEMjzuE4/VMAA/M/mQww15F9VrWAqONaqYMDhkPmx wwKfZ+1YKjimQuzijSaYVTc5iQ/aVOnuSxkiLhMKAxWwtC/gu8osfmTTvcK1r95r4ExfcEeVx WZYubXbu/k9uQFFpfTBlZC3Y43kcbGCnNS7W6ctry/VIGAMPxCJ2YlUnS2wBpvtIEwHdRaPkB PWX2wS8APoTILT59cy+r8HmYmRpvJ9plQTe6Hd4/s1Yf3I8oooggHA8AoT1DkLq9NlyEnR6BJ GZ9oblcwKkie3avd3EohLgtdU+ykyt3RylPo1RQad4rZh4QTYsCLRJXO9C/S8xRkh3+WBzik+ iMXn8drwSvgEzccg0bYQnmFJWY0a1cCIVL7SHxMlExAh29b1GjE/ODEcgdrGt5MyUhIpkB9aX t7+rYYu5n66Xvt5ABeQqxh92Nconma2hsjHTLKcdyLg3bno68wC5X5H+W+qQB1zQWIzodKYJ7 OohjwXPg70ZxzUeG/SE1ly0cirJb7AAG04DoV9KlHjQ50hJfP3XVadLDXDsiK8EIu3y0FHLnC V8Mr5qSlJs4oXF1wkOBFWq6eV7nB3PiPQmvehGheeZ+sGjMixvt3RkwvLZjBQbilTceEhgk41 V9kN6XFgCbLJStlykmMOMIPCrB8/Qamv+KAN9w== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 93cbbcbbc193..d0b786078bea 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; 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; 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; MISSING_CASE(voltage); + } return NULL; } else { return cnl_get_buf_trans_dp(dev_priv, n_entries); -- 2.9.0