i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl

In the Linux kernel, the following vulnerability has been resolved:

i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl

While fuzzing with Syzkaller, a persistent schedule_timeout: wrong timeout value warning was observed, accompanied by SMBus controller state machine corruption.

The I2C_TIMEOUT ioctl accepts a user-provided timeout in multiples of 10 ms. The user argument is checked against INT_MAX, but it is subsequently multiplied by 10 before being passed to msecs_to_jiffies().

A malicious user can pass a large value (e.g., 429496729) that passes the arg > INT_MAX check but overflows when multiplied by 10. This results in a truncated 32-bit unsigned value that bypasses the internal (int)m < 0 check in msecs_to_jiffies().

The truncated value is then assigned to client->adapter->timeout (a signed 32-bit int), which is reinterpreted as a negative number. When passed to wait_for_completion_timeout(), this negative value undergoes sign extension to a 64-bit unsigned long, triggering the schedule_timeout warning and causing premature returns. This leaves the SMBus state machine in an unrecoverable state, constituting a local Denial of Service (DoS).

Fix this by bounding the user argument to INT_MAX / 10.

[wsa: move the comment as well]