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authorVille Syrjälä <ville.syrjala@linux.intel.com>2017-11-23 21:41:57 +0200
committerJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2017-11-28 10:31:42 +0200
commit56350fb8978bbf4aafe08f21234e161dd128b417 (patch)
treea320fd79bf0af4ebcc115e6f980a00474a55b3a0
parentae5c631e605a452a5a0e73205a92810c01ed954b (diff)
drm/i915: Prevent zero length "index" write
The hardware always writes one or two bytes in the index portion of an indexed transfer. Make sure the message we send as the index doesn't have a zero length. Cc: stable@vger.kernel.org Cc: Daniel Kurtz <djkurtz@chromium.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sean Paul <seanpaul@chromium.org> Fixes: 56f9eac05489 ("drm/i915/intel_i2c: use INDEX cycles for i2c read transactions") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20171123194157.25367-3-ville.syrjala@linux.intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (cherry picked from commit bb9e0d4bca50f429152e74a459160b41f3d60fb2) Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
-rw-r--r--drivers/gpu/drm/i915/intel_i2c.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 8affd47b98b8..49fdf09f9919 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -439,7 +439,8 @@ gmbus_is_index_read(struct i2c_msg *msgs, int i, int num)
{
return (i + 1 < num &&
msgs[i].addr == msgs[i + 1].addr &&
- !(msgs[i].flags & I2C_M_RD) && msgs[i].len <= 2 &&
+ !(msgs[i].flags & I2C_M_RD) &&
+ (msgs[i].len == 1 || msgs[i].len == 2) &&
(msgs[i + 1].flags & I2C_M_RD));
}