From a92d1a91cf729c585b978cecb75b046ced0bc164 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Wed, 10 May 2017 12:21:52 +0300 Subject: [PATCH] drm/i915: Sanitize stolen memory size calculation MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On GEN8+ (not counting CHV) the calculation can in theory result in an incorrect sign extension with all upper bits set. In practice this is unlikely to happen since it would require 4GB of stolen memory set aside. For consistency still prevent the sign extension explicitly everywhere. Signed-off-by: Imre Deak Reviewed-by: Ville Syrjälä Link: http://patchwork.freedesktop.org/patch/msgid/1494408113-379-6-git-send-email-imre.deak@intel.com --- drivers/gpu/drm/i915/i915_gem_gtt.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c index 0178c9eba70a..ac2b8f64c770 100644 --- a/drivers/gpu/drm/i915/i915_gem_gtt.c +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c @@ -2577,14 +2577,14 @@ static size_t gen6_get_stolen_size(u16 snb_gmch_ctl) { snb_gmch_ctl >>= SNB_GMCH_GMS_SHIFT; snb_gmch_ctl &= SNB_GMCH_GMS_MASK; - return snb_gmch_ctl << 25; /* 32 MB units */ + return (size_t)snb_gmch_ctl << 25; /* 32 MB units */ } static size_t gen8_get_stolen_size(u16 bdw_gmch_ctl) { bdw_gmch_ctl >>= BDW_GMCH_GMS_SHIFT; bdw_gmch_ctl &= BDW_GMCH_GMS_MASK; - return bdw_gmch_ctl << 25; /* 32 MB units */ + return (size_t)bdw_gmch_ctl << 25; /* 32 MB units */ } static size_t chv_get_stolen_size(u16 gmch_ctrl) @@ -2598,11 +2598,11 @@ static size_t chv_get_stolen_size(u16 gmch_ctrl) * 0x17 to 0x1d: 4MB increments start at 36MB */ if (gmch_ctrl < 0x11) - return gmch_ctrl << 25; + return (size_t)gmch_ctrl << 25; else if (gmch_ctrl < 0x17) - return (gmch_ctrl - 0x11 + 2) << 22; + return (size_t)(gmch_ctrl - 0x11 + 2) << 22; else - return (gmch_ctrl - 0x17 + 9) << 22; + return (size_t)(gmch_ctrl - 0x17 + 9) << 22; } static size_t gen9_get_stolen_size(u16 gen9_gmch_ctl) @@ -2611,10 +2611,10 @@ static size_t gen9_get_stolen_size(u16 gen9_gmch_ctl) gen9_gmch_ctl &= BDW_GMCH_GMS_MASK; if (gen9_gmch_ctl < 0xf0) - return gen9_gmch_ctl << 25; /* 32 MB units */ + return (size_t)gen9_gmch_ctl << 25; /* 32 MB units */ else /* 4MB increments starting at 0xf0 for 4MB */ - return (gen9_gmch_ctl - 0xf0 + 1) << 22; + return (size_t)(gen9_gmch_ctl - 0xf0 + 1) << 22; } static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size) -- 2.20.1