CVE-2026-64083hwmon: (pmbus/adm1266) reject short block-read responses in the GPIO accessors

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fd9196aad9e5a3845cea17de3405ebc700382142
• https://git.kernel.org/stable/c/ee4799becf7d2af3778007e22c2e55c4009a49c7
• https://git.kernel.org/stable/c/c603b6c6840ac0c6285f5eefea0de6242710af21
• https://git.kernel.org/stable/c/a2d1c819348b36fccbbfcf37c5fa7a50a9b4528f
• https://git.kernel.org/stable/c/ae25cf2ea9ebd06d7ad416647dbdc7b5d0172946
• https://git.kernel.org/stable/c/eb3cd9bb590460c6127145cb245be925d23f5232
• https://git.kernel.org/stable/c/64fa9328948ddcc0f7f3c23ea1756c126d9dffac
• https://git.kernel.org/stable/c/a7232f68c43ca62f545049b7f5fbfc75137b843b