4.17-stable review patch. If anyone has any objections, please let me know.
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From: Wenwen Wang wang6495@umn.edu
commit 8e03477cb709b73a2c1e1f4349ee3b7b33c50416 upstream.
In i2c_smbus_xfer_emulated(), the function i2c_transfer() is invoked to transfer i2c messages. The number of actual transferred messages is returned and saved to 'status'. If 'status' is negative, that means an error occurred during the transfer process. In that case, the value of 'status' is an error code to indicate the reason of the transfer failure. In most cases, i2c_transfer() can transfer 'num' messages with no error. And so 'status' == 'num'. However, due to unexpected errors, it is probable that only partial messages are transferred by i2c_transfer(). As a result, 'status' != 'num'. This special case is not checked after the invocation of i2c_transfer() and can potentially lead to unexpected issues in the following execution since it is expected that 'status' == 'num'.
This patch checks the return value of i2c_transfer() and returns an error code -EIO if the number of actual transferred messages 'status' is not equal to 'num'.
Signed-off-by: Wenwen Wang wang6495@umn.edu Signed-off-by: Wolfram Sang wsa@the-dreams.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/i2c/i2c-core-smbus.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -466,6 +466,8 @@ static s32 i2c_smbus_xfer_emulated(struc status = i2c_transfer(adapter, msg, num); if (status < 0) return status; + if (status != num) + return -EIO;
/* Check PEC if last message is a read */ if (i && (msg[num-1].flags & I2C_M_RD)) {