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

adm1266gpioget() and adm1266gpioget_multiple() both compose the pin-status word as

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

right after i2csmbusreadblockdata(), guarding only against an error return. A well-behaved device returns 2 bytes for GPIOSTATUS/PDIOSTATUS, but the helper happily reports a 0- or 1-byte response too. If the device returns 0 bytes, both readbuf slots are uninitialized stack memory; if it returns 1 byte, readbuf[1] is.

The composed value then flows through setbit() into the caller's *bits in adm1266gpiogetmultiple(), or into the return value of adm1266gpioget(), 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.