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

Overview

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.

Affected

• Linux >= 8646a3b5ee3a5b384a22a721f37c24274d974045 < 21243c15e1d31f0df1517435e3a7784747f19043
• Linux >= 8646a3b5ee3a5b384a22a721f37c24274d974045 < cecb8154bd5fa6c8ddbd1a4e8216bbc0f0eb9828
• Linux >= 8646a3b5ee3a5b384a22a721f37c24274d974045 < 0f9aad08424882dd5714b53d29ae044060890752
• Linux >= 8646a3b5ee3a5b384a22a721f37c24274d974045 < b699e5c1f63a9e79946c35598c8a6f7af2c356b8
• Linux >= 8646a3b5ee3a5b384a22a721f37c24274d974045 < 2b2ec354f905c14e3270e8ec3ab50f7d8ad73bab
• Linux 6.6

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · updated 2026-09-14 · vex