6.18-stable review patch. If anyone has any objections, please let me know.

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From: Cryolitia PukNgae cryolitia.pukngae@linux.dev

[ Upstream commit 9d6c58dae8f6590c746ac5d0012ffe14a77539f0 ]

Although commit 0c9992315e73 ("ACPICA: Avoid walking the ACPI Namespace if it is not there") fixed the situation when both start_node and acpi_gbl_root_node are NULL, the Linux kernel mainline now still crashed on Honor Magicbook 14 Pro [1].

That happens due to the access to the member of parent_node in acpi_ns_get_next_node(). The NULL pointer dereference will always happen, no matter whether or not the start_node is equal to ACPI_ROOT_OBJECT, so move the check of start_node being NULL out of the if block.

Unfortunately, all the attempts to contact Honor have failed, they refused to provide any technical support for Linux.

The bad DSDT table's dump could be found on GitHub [2].

DMI: HONOR FMB-P/FMB-P-PCB, BIOS 1.13 05/08/2025

Link: https://github.com/acpica/acpica/commit/1c1b57b9eba4554cb132ee658dd942c0210e... Link: https://gist.github.com/Cryolitia/a860ffc97437dcd2cd988371d5b73ed7 [1] Link: https://github.com/denis-bb/honor-fmb-p-dsdt [2] Signed-off-by: Cryolitia PukNgae cryolitia.pukngae@linux.dev Reviewed-by: WangYuli wangyl5933@chinaunicom.cn [ rjw: Subject adjustment, changelog edits ] Link: https://patch.msgid.link/20251125-acpica-v1-1-99e63b1b25f8@linux.dev Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/acpica/nswalk.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpica/nswalk.c b/drivers/acpi/acpica/nswalk.c index a2ac06a26e921..5670ff5a43cd4 100644 --- a/drivers/acpi/acpica/nswalk.c +++ b/drivers/acpi/acpica/nswalk.c @@ -169,9 +169,12 @@ acpi_ns_walk_namespace(acpi_object_type type,

if (start_node == ACPI_ROOT_OBJECT) { start_node = acpi_gbl_root_node; - if (!start_node) { - return_ACPI_STATUS(AE_NO_NAMESPACE); - } + } + + /* Avoid walking the namespace if the StartNode is NULL */ + + if (!start_node) { + return_ACPI_STATUS(AE_NO_NAMESPACE); }

/* Null child means "get first node" */