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Sat, 04 Jul 2026 09:08:29 -0700 (PDT) Received: from node ([202.47.63.86]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c12b60575c4sm438586266b.9.2026.07.04.09.08.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 Jul 2026 09:08:29 -0700 (PDT) From: Muhammad Bilal To: hdegoede@redhat.com, ilpo.jarvinen@linux.intel.com, jorge.lopez2@hp.com, Thomas.Weissschuh@linutronix.de, platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, Mario Limonciello , Armin Wolf , Muhammad Bilal Subject: [PATCH v2 0/3] hp-bioscfg: fix attribute enumeration on older HP BIOS Date: Sat, 4 Jul 2026 21:07:56 +0500 Message-ID: <20260704160759.236249-1-meatuni001@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The hp_bioscfg driver fails to enumerate BIOS attributes on HP EliteBook 840 G2 (and potentially other older HP models) because: 1. hp_init_bios_package_attribute() hard-fails when a WMI ACPI package contains fewer elements than the per-type expected count (11 < 13), even though only the first 10 common elements are required to register an attribute. 2. hp_populate_enumeration_elements_from_package() returns -EIO and discards the entire attribute when any single element has an unexpected ACPI object type - typically after a BIOS AML error returns malformed data. Hardware affected: HP EliteBook 840 G2 (DMI: Hewlett-Packard HP EliteBook 840 G2/2216) BIOS: M71 Ver. 01.31 (02/24/2020) How to reproduce: 1. Boot a kernel with CONFIG_HP_BIOSCFG=m on an HP EliteBook 840 G2 2. modprobe hp_bioscfg 3. Observe dmesg: hp_bioscfg: ACPI-package does not have enough elements: 11 < 13 Error expected type 2 for elem 13, but got type 1 instead Changes since v1: Patch 1/3 is new. Relaxing the element-count gate in patch 2/3 (v1's patch 1/2) lets packages shorter than the per-type ELEM_CNT constant reach hp_populate_*_elements_from_package(). Those loops don't bound themselves against the real package size - each one re-derives a "count" by reading ->package.count off elements[0], which is always a string (NAME) object, so it's actually reading ->string.length through the union. That was harmless while the old hard min_elements gate guaranteed a full ELEM_CNT-sized package on every call, but once patch 2/3 allows a shorter package through, the fixed ELEM_CNT loop bound walks past the end of the real elements[] array - a heap out-of-bounds read, on the exact EliteBook 840 G2 hardware this series targets. Patch 1/3 fixes this by threading the real, already-validated obj->package.count down into every hp_populate_*_package_data() wrapper instead of letting each one guess at it, and bounds hp_populate_ordered_list_elements_from_package()'s main loop (which previously ignored the count entirely) the same way. It's a no-op for any package that already meets today's ELEM_CNT minimums, and patch 2/3 is only safe to apply on top of it. Patches 2/3 and 3/3 are otherwise unchanged from v1. Thanks to Mario for the v1 Reviewed-by, carried forward on 2/3 and 3/3 since those are unmodified. Armin's point about migrating to the buffer-based WMI API for correct marshaling is well taken as the longer-term fix; this series is meant as a minimal, backportable fix for the immediate enumeration failure and the OOB read it would otherwise reintroduce, not a replacement for that migration. Testing notes: Tested on HP EliteBook 840 G2 running Arch Linux kernel 7.0.13-arch1-1. After patches, hp_bioscfg loads successfully and enumerates available BIOS attributes. Attributes with shortened packages are partially populated and accessible via sysfs. No regressions on systems that return full ELEM_CNT-element packages (patch 1/3 only changes behavior once patch 2/3's relaxed gate can hand it a shorter one). Relevant dmesg (before fix): [ 11.xxx] hp_bioscfg: ACPI-package does not have enough elements: 11 < 13 [ 11.xxx] ACPI BIOS Error (bug): AE_AML_BUFFER_LIMIT, Index (0x000000032) is beyond end of object (length 0x32) [ 11.xxx] ACPI Error: Aborting method \_SB.WMID.WQBE [ 11.xxx] Error expected type 2 for elem 13, got type 1 [ 11.xxx] hp_bioscfg: Returned error 0x3 Muhammad Bilal (3): platform/x86: hp-bioscfg: pass validated element count to package parsers platform/x86: hp-bioscfg: accept reduced ACPI packages from older HP BIOS platform/x86: hp-bioscfg: warn on element type mismatch instead of failing drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 16 +++++++++++++--- drivers/platform/x86/hp/hp-bioscfg/bioscfg.h | 8 ++++++++ .../platform/x86/hp/hp-bioscfg/enum-attributes.c | 10 ++++++---- .../platform/x86/hp/hp-bioscfg/int-attributes.c | 3 ++- .../x86/hp/hp-bioscfg/order-list-attributes.c | 7 ++++--- .../x86/hp/hp-bioscfg/passwdobj-attributes.c | 5 +++-- .../x86/hp/hp-bioscfg/string-attributes.c | 3 ++- 7 files changed, 38 insertions(+), 14 deletions(-) -- 2.55.0