From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Vetter , Dave Airlie Subject: [PATCH 4.2 42/54] drm/dp/mst: make mst i2c transfer code more robust. Date: Fri, 23 Oct 2015 10:45:18 -0700 Message-Id: <20151023174520.347281995@linuxfoundation.org> In-Reply-To: <20151023174519.086915553@linuxfoundation.org> References: <20151023174519.086915553@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Airlie commit ae491542cbbbcca0ec8938c37d4079a985e58440 upstream. This zeroes the msg so no random stack data ends up getting sent, it also limits the function to not accepting > 4 i2c msgs. Reviewed-by: Daniel Vetter Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_mst_topology.c | 3 ++- include/drm/drm_dp_mst_helper.h | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2789,12 +2789,13 @@ static int drm_dp_mst_i2c_xfer(struct i2 if (msgs[num - 1].flags & I2C_M_RD) reading = true; - if (!reading) { + if (!reading || (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)) { DRM_DEBUG_KMS("Unsupported I2C transaction for MST device\n"); ret = -EIO; goto out; } + memset(&msg, 0, sizeof(msg)); msg.req_type = DP_REMOTE_I2C_READ; msg.u.i2c_read.num_transactions = num - 1; msg.u.i2c_read.port_number = port->port_num; --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -253,6 +253,7 @@ struct drm_dp_remote_dpcd_write { u8 *bytes; }; +#define DP_REMOTE_I2C_READ_MAX_TRANSACTIONS 4 struct drm_dp_remote_i2c_read { u8 num_transactions; u8 port_number; @@ -262,7 +263,7 @@ struct drm_dp_remote_i2c_read { u8 *bytes; u8 no_stop_bit; u8 i2c_transaction_delay; - } transactions[4]; + } transactions[DP_REMOTE_I2C_READ_MAX_TRANSACTIONS]; u8 read_i2c_device_id; u8 num_bytes_read; };