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authorVille Syrjälä <ville.syrjala@linux.intel.com>2017-11-23 21:41:57 +0200
committerSasha Levin <alexander.levin@verizon.com>2017-12-08 18:01:17 -0500
commit2f952d47911f36766122918cc4e6ae782780f513 (patch)
treebd2b0452e5a2bc099e643beb881a5e064ce9c7b7
parentb504b57060a2f285de5393dabfc64d71d654e748 (diff)
drm/i915: Prevent zero length "index" write
[ Upstream commit 56350fb8978bbf4aafe08f21234e161dd128b417 ] 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> Signed-off-by: Sasha Levin <alexander.levin@verizon.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 6f3b747eeda5..b4891066a369 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -395,7 +395,8 @@ 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));
}