CVE-2026-64083

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

hwmon: (pmbus/adm1266) reject short block-read responses in the GPIO accessors

adm1266_gpio_get() and adm1266_gpio_get_multiple() both compose the

pin-status word as

pins_status = read_buf[0] + (read_buf[1] << 8);

right after i2c_smbus_read_block_data(), guarding only against an

error return. A well-behaved device returns 2 bytes for

GPIO_STATUS/PDIO_STATUS, but the helper happily reports a 0- or

1-byte response too. If the device returns 0 bytes, both read_buf

slots are uninitialized stack memory; if it returns 1 byte, read_buf[1]

is.

The composed value then flows through set_bit() into the caller's

*bits in adm1266_gpio_get_multiple(), or into the return value of

adm1266_gpio_get(), and ends up in userspace via gpiolib (sysfs and

the char-dev ioctls). That leaks a few bits of kernel stack per

request on any device whose firmware glitch, bus error, or hostile

slave produces a short block-read response.

Add the missing length check to both call sites and surface a short

response as -EIO.