CVE-2022-50394

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

i2c: ismt: Fix an out-of-bounds bug in ismt_access()

When the driver does not check the data from the user, the variable 'data->block[0]' may be very large to cause an out-of-bounds bug.

The following log can reveal it:

[ 33.995542] i2c i2c-1: ioctl, cmd=0x720, arg=0x7ffcb3dc3a20 [ 33.995978] ismt_smbus 0000:00:05.0: I2C_SMBUS_BLOCK_DATA: WRITE [ 33.996475] ================================================================== [ 33.996995] BUG: KASAN: out-of-bounds in ismt_access.cold+0x374/0x214b [ 33.997473] Read of size 18446744073709551615 at addr ffff88810efcfdb1 by task ismt_poc/485 [ 33.999450] Call Trace: [ 34.001849] memcpy+0x20/0x60 [ 34.002077] ismt_access.cold+0x374/0x214b [ 34.003382] __i2c_smbus_xfer+0x44f/0xfb0 [ 34.004007] i2c_smbus_xfer+0x10a/0x390 [ 34.004291] i2cdev_ioctl_smbus+0x2c8/0x710 [ 34.005196] i2cdev_ioctl+0x5ec/0x74c

Fix this bug by checking the size of 'data->block[0]' first.

The Intel iSMT SMBus driver failed to validate the SMBus block length (data->block[0]) in ismt_access(), enabling an out-of-bounds copy and kernel crash via ioctl(I2C_SMBUS). Exploitation is local and typically requires access to /dev/i2c-* (root by default), so the practical impact is a kernel DoS rather than memory disclosure or code execution.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.