From cb8ce7111117e16a87f3f55c014ccd1f19f81016 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Fri, 28 Sep 2018 21:04:00 +0300 Subject: [PATCH] drm/dp/mst: Validate REMOTE_I2C_READ harder MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Make sure i2c msgs we're asked to transfer conform to the requirements of REMOTE_I2C_READ. We were only checking that the last message is a read, but we must also check that the preceding messages are all writes. Also check that the length of each message isn't too long. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20180928180403.22499-2-ville.syrjala@linux.intel.com Reviewed-by: Dhinakaran Pandiyan --- drivers/gpu/drm/drm_dp_mst_topology.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 229ad6026314..f0cbd5fad8fc 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -3250,6 +3250,23 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr) } EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy); +static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num) +{ + int i; + + if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS) + return false; + + for (i = 0; i < num - 1; i++) { + if (msgs[i].flags & I2C_M_RD || + msgs[i].len > 0xff) + return false; + } + + return msgs[num - 1].flags & I2C_M_RD && + msgs[num - 1].len <= 0xff; +} + /* I2C device */ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num) @@ -3259,7 +3276,6 @@ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs struct drm_dp_mst_branch *mstb; struct drm_dp_mst_topology_mgr *mgr = port->mgr; unsigned int i; - bool reading = false; struct drm_dp_sideband_msg_req_body msg; struct drm_dp_sideband_msg_tx *txmsg = NULL; int ret; @@ -3268,12 +3284,7 @@ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs if (!mstb) return -EREMOTEIO; - /* construct i2c msg */ - /* see if last msg is a read */ - if (msgs[num - 1].flags & I2C_M_RD) - reading = true; - - if (!reading || (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)) { + if (!remote_i2c_read_ok(msgs, num)) { DRM_DEBUG_KMS("Unsupported I2C transaction for MST device\n"); ret = -EIO; goto out; -- 2.11.0