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SubjectRE: [PATCH] ACPICA:dbnames: Fix a error free in acpi_db_walk_for_fields
Date


> -----Original Message-----
> From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> Sent: Monday, April 26, 2021 6:42 PM
> To: Moore, Robert <robert.moore@intel.com>; Kaneda, Erik
> <erik.kaneda@intel.com>; Wysocki, Rafael J <rafael.j.wysocki@intel.com>;
> lenb@kernel.org
> Cc: linux-acpi@vger.kernel.org; devel@acpica.org; linux-
> kernel@vger.kernel.org; Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> Subject: [PATCH] ACPICA:dbnames: Fix a error free in
> acpi_db_walk_for_fields
>
> In acpi_db_walk_for_fields, buffer.pointer is freed in the first
> time via ACPI_FREE() after acpi_os_printf("%s ", (char *)buffer.pointer).
> But later, buffer.pointer is assigned to ret_value, and the freed
> pointer is dereferenced by ret_value, which is use after free.
>
> In addition, buffer.pointer is freed by ACPI_FREE() again after
> acpi_os_printf("}\n"), which is a double free.
>
> My patch removes the first ACPI_FREE() to avoid the uaf and double
> free bugs.
>

I'll take a look

Thanks

> Fixes: 5fd033288a866 ("ACPICA: debugger: add command to dump all fields
> of particular subtype")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> ---
> drivers/acpi/acpica/dbnames.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/acpi/acpica/dbnames.c b/drivers/acpi/acpica/dbnames.c
> index 3615e1a6efd8..dabd76df15ec 100644
> --- a/drivers/acpi/acpica/dbnames.c
> +++ b/drivers/acpi/acpica/dbnames.c
> @@ -547,7 +547,6 @@ acpi_db_walk_for_fields(acpi_handle obj_handle,
> }
>
> acpi_os_printf("%s ", (char *)buffer.pointer);
> - ACPI_FREE(buffer.pointer);
>
> buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
> acpi_evaluate_object(obj_handle, NULL, NULL, &buffer);
> --
> 2.25.1
>

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