Affected: Alpaquita:25: linux-lts, Alpaquita:stream: linux-lts

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.

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.

kernel-devel-7.2.6-1.1 on GA media

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 154 more

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.

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um Sicherheitsmaßnahmen zu umgehen, Daten oder den Systemzustand zu manipulieren, Denial-of-Service-Zustände herbeizuführen oder andere, nicht näher spezifizierte Angriffe durchzuführen.