[PATCH 4.9 07/61] Input: elan_i2c_smbus - fix corrupted stack

Greg Kroah-Hartman
2018-06-05T17:05:13Z

From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

commit 40f7090bb1b4ec327ea1e1402ff5783af5b35195 upstream.

New ICs (like the one on the Lenovo T480s) answer to
ETP_SMBUS_IAP_VERSION_CMD 4 bytes instead of 3. This corrupts the stack
as i2c_smbus_read_block_data() uses the values returned by the i2c
device to know how many data it need to return.

i2c_smbus_read_block_data() can read up to 32 bytes (I2C_SMBUS_BLOCK_MAX)
and there is no safeguard on how many bytes are provided in the return
value. Ensure we always have enough space for any future firmware.
Also 0-initialize the values to prevent any access to uninitialized memory.

Cc: <stable@vger.kernel.org> # v4.4.x, v4.9.x, v4.14.x, v4.15.x, v4.16.x
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/input/mouse/elan_i2c_smbus.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

--- a/drivers/input/mouse/elan_i2c_smbus.c
+++ b/drivers/input/mouse/elan_i2c_smbus.c
@@ -130,7 +130,7 @@ static int elan_smbus_get_baseline_data(
bool max_baseline, u8 *value)
{
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client,
max_baseline ?
@@ -149,7 +149,7 @@ static int elan_smbus_get_version(struct
bool iap, u8 *version)
{
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client,
iap ? ETP_SMBUS_IAP_VERSION_CMD :
@@ -169,7 +169,7 @@ static int elan_smbus_get_sm_version(str
u8 *ic_type, u8 *version)
{
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client,
ETP_SMBUS_SM_VERSION_CMD, val);
@@ -186,7 +186,7 @@ static int elan_smbus_get_sm_version(str
static int elan_smbus_get_product_id(struct i2c_client *client, u16 *id)
{
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client,
ETP_SMBUS_UNIQUEID_CMD, val);
@@ -203,7 +203,7 @@ static int elan_smbus_get_checksum(struc
bool iap, u16 *csum)
{
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client,
iap ? ETP_SMBUS_FW_CHECKSUM_CMD :
@@ -224,7 +224,7 @@ static int elan_smbus_get_max(struct i2c
{
int ret;
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

ret = i2c_smbus_read_block_data(client, ETP_SMBUS_RANGE_CMD, val);
if (ret != 3) {
@@ -244,7 +244,7 @@ static int elan_smbus_get_resolution(str
{
int ret;
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

ret = i2c_smbus_read_block_data(client, ETP_SMBUS_RESOLUTION_CMD, val);
if (ret != 3) {
@@ -265,7 +265,7 @@ static int elan_smbus_get_num_traces(str
{
int ret;
int error;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

ret = i2c_smbus_read_block_data(client, ETP_SMBUS_XY_TRACENUM_CMD, val);
if (ret != 3) {
@@ -292,7 +292,7 @@ static int elan_smbus_iap_get_mode(struc
{
int error;
u16 constant;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

error = i2c_smbus_read_block_data(client, ETP_SMBUS_IAP_CTRL_CMD, val);
if (error < 0) {
@@ -343,7 +343,7 @@ static int elan_smbus_prepare_fw_update(
int len;
int error;
enum tp_mode mode;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};
u8 cmd[4] = {0x0F, 0x78, 0x00, 0x06};
u16 password;

@@ -417,7 +417,7 @@ static int elan_smbus_write_fw_block(str
struct device *dev = &client->dev;
int error;
u16 result;
- u8 val[3];
+ u8 val[I2C_SMBUS_BLOCK_MAX] = {0};

/*
* Due to the limitation of smbus protocol limiting