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drm/dp/mst: make mst i2c transfer code more robust.

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This zeroes the msg so no random stack data ends up getting
sent, it also limits the function to not accepting > 4
i2c msgs.

Cc: stable@vger.kernel.org
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Dave Airlie 2015-10-14 18:51:17 +10:00 committed by Dave Airlie
parent bc8c131ccd
commit ae491542cb
2 changed files with 4 additions and 2 deletions
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3
drivers/gpu/drm/drm_dp_mst_topology.c
View file

@ -2801,12 +2801,13 @@ static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs
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;

3
include/drm/drm_dp_mst_helper.h
View file

@ -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;
};