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authorVille Syrjälä <ville.syrjala@linux.intel.com>2017-11-23 21:41:57 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-12-05 11:24:35 +0100
commitf990312aaa74faf14d00a1b050c55a66dfe3153a (patch)
tree52791cc675df2779d68cfa3453714fd525600786
parent838cdb26a538aa83326639f53ce4f8112f23dd96 (diff)
drm/i915: Prevent zero length "index" write
commit 56350fb8978bbf4aafe08f21234e161dd128b417 upstream. 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: 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 f8b406b88c77..6769aa1b6922 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -431,7 +431,8 @@ 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));
}