From: Ville Syrjälä Date: Thu, 23 Nov 2017 19:41:57 +0000 (+0200) Subject: drm/i915: Prevent zero length "index" write X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=bb9e0d4bca50f429152e74a459160b41f3d60fb2;p=openwrt%2Fstaging%2Fblogic.git 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 Cc: Chris Wilson Cc: Daniel Vetter Cc: Sean Paul Fixes: 56f9eac05489 ("drm/i915/intel_i2c: use INDEX cycles for i2c read transactions") Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20171123194157.25367-3-ville.syrjala@linux.intel.com Reviewed-by: Chris Wilson --- 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)); }