CVE-2026-81013

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

platform/x86: hp-bioscfg: fix heap OOB read on empty password write

validate_password_input() computes length = strlen(buf) and then

checks buf[length - 1] to strip a trailing newline, without checking

that length is nonzero first. Writing an empty string (a bare '\n')

to current_password or new_password gives length == 0, and

buf[length - 1] reads buf[-1], one byte before the heap allocation

holding the copied input.

KASAN confirms this directly:

BUG: KASAN: slab-out-of-bounds in store_password_instance.constprop.0+0x223/0x2a0 [hp_bioscfg]

Read of size 1 at addr ffff88811bd8da9f by task sh/13740

...

store_password_instance.constprop.0+0x223/0x2a0 [hp_bioscfg]

current_password_store+0x14/0x20 [hp_bioscfg]

...

The buggy address is located 23 bytes to the right of

allocated 8-byte region [ffff88811bd8da80, ffff88811bd8da88)

Reproduced identically via new_password_store. Execution continues

past the bad read (the garbage byte only affects whether "length" is

decremented by one), so the write completes and returns success; this

is a pure information read past the buffer, not a crash, but it is

still an out-of-bounds access KASAN correctly flags.

Fix by only checking buf[length - 1] when length is nonzero.