Re: [PATCH] ACPICA: fix NULL pointer dereference in acpi_ns_custom_package()

On Sun, Mar 22, 2026 at 4:36 PM Weiming Shi <[email protected]> wrote:
>
> acpi_ns_custom_package() unconditionally dereferences the first element
> of the package to read the _BIX version number, without checking for
> NULL:
>
>   if ((*elements)->common.type != ACPI_TYPE_INTEGER)
>
> When firmware returns a _BIX package whose first element is an
> unresolvable reference, ACPICA evaluates that entry to NULL.
> acpi_ns_remove_null_elements() does not strip NULL entries for
> ACPI_PTYPE_CUSTOM packages (fixed-position format would break if
> elements were shifted), so acpi_ns_custom_package() sees the NULL
> and panics.
>
>  general protection fault, probably for non-canonical address
>  0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
>  KASAN: null-ptr-deref in range
>  [0x0000000000000008-0x000000000000000f]
>  RIP: acpi_ns_check_package
>  (drivers/acpi/acpica/nsprepkg.c:634
>   drivers/acpi/acpica/nsprepkg.c:110)
>  Call Trace:
>   <TASK>
>   acpi_ns_check_return_value (nspredef.c:136)
>   acpi_ns_evaluate (nseval.c:266)
>   acpi_evaluate_object (nsxfeval.c:360)
>   acpi_battery_get_info (battery.c:537)
>   acpi_battery_update (battery.c:1007)
>   acpi_battery_add (battery.c:1237)
>   acpi_device_probe (bus.c:1076)
>   really_probe (dd.c:659)
>   </TASK>
>
> Add a NULL check for the first element (version field) before
> dereferencing it. The battery probe then fails gracefully with
> AE_AML_OPERAND_TYPE instead of crashing the kernel.
>
> Required CONFIG: CONFIG_ACPI_BATTERY=y
>
> Fixes: 7952d40240855932 ("ACPICA: ACPI 6.0: Update _BIX support for new package element")
> Reported-by: Xiang Mei <[email protected]>
> Signed-off-by: Weiming Shi <[email protected]>
> ---
>  drivers/acpi/acpica/nsprepkg.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/acpi/acpica/nsprepkg.c b/drivers/acpi/acpica/nsprepkg.c
> index ca137ce5674f..c32770570120 100644
> --- a/drivers/acpi/acpica/nsprepkg.c
> +++ b/drivers/acpi/acpica/nsprepkg.c
> @@ -631,6 +631,13 @@ acpi_ns_custom_package(struct acpi_evaluate_info *info,
>
>         /* Get version number, must be Integer */
>
> +       if (!(*elements)) {
> +               ACPI_WARN_PREDEFINED((AE_INFO, info->full_pathname,
> +                                     info->node_flags,
> +                                     "Return Package has a NULL version element"));
> +               return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
> +       }
> +
>         if ((*elements)->common.type != ACPI_TYPE_INTEGER) {
>                 ACPI_WARN_PREDEFINED((AE_INFO, info->full_pathname,
>                                       info->node_flags,
> --

ACPICA changes need to be routed via upstream ACPICA project on GitHub.

Please see Documentation/driver-api/acpi/linuxized-acpica.rst