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Message-ID: <202301151037.20CC3F0@keescook>
Date: Sun, 15 Jan 2023 10:38:48 -0800
From: Kees Cook <keescook@...omium.org>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Len Brown <lenb@...nel.org>, Robert Moore <robert.moore@...el.com>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
linux-acpi@...r.kernel.org, devel@...ica.org,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] ACPICA: Replace fake flexible arrays with flexible array
members
On Fri, Nov 18, 2022 at 10:15:51AM -0800, Kees Cook wrote:
> Functionally identical to ACPICA upstream pull request 813:
> https://github.com/acpica/acpica/pull/813
Any update on this? Upstream is currently unbuildable since October.
> One-element arrays (and multi-element arrays being treated as
> dynamically sized) are deprecated[1] and are being replaced with
> flexible array members in support of the ongoing efforts to tighten the
> FORTIFY_SOURCE routines on memcpy(), correctly instrument array indexing
> with UBSAN_BOUNDS, and to globally enable -fstrict-flex-arrays=3.
>
> Replace one-element array with flexible-array member in struct
> acpi_resource_extended_irq. Replace 4-byte fixed-size array with 4-byte
> padding in a union with a flexible-array member in struct
> acpi_pci_routing_table.
>
> This results in no differences in binary output.
In the meantime, can you take this patch for Linux, and we can wait for
ACPICA to catch up?
Thanks!
-Kees
>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Cc: Len Brown <lenb@...nel.org>
> Cc: Robert Moore <robert.moore@...el.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@...nel.org>
> Cc: linux-acpi@...r.kernel.org
> Cc: devel@...ica.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
> include/acpi/acrestyp.h | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/acpi/acrestyp.h b/include/acpi/acrestyp.h
> index a7fb8ddb3dc6..ee945084d46e 100644
> --- a/include/acpi/acrestyp.h
> +++ b/include/acpi/acrestyp.h
> @@ -332,7 +332,7 @@ struct acpi_resource_extended_irq {
> u8 wake_capable;
> u8 interrupt_count;
> struct acpi_resource_source resource_source;
> - u32 interrupts[1];
> + u32 interrupts[];
> };
>
> struct acpi_resource_generic_register {
> @@ -679,7 +679,10 @@ struct acpi_pci_routing_table {
> u32 pin;
> u64 address; /* here for 64-bit alignment */
> u32 source_index;
> - char source[4]; /* pad to 64 bits so sizeof() works in all cases */
> + union {
> + char pad[4]; /* pad to 64 bits so sizeof() works in all cases */
> + DECLARE_FLEX_ARRAY(char, source);
> + };
> };
>
> #endif /* __ACRESTYP_H__ */
> --
> 2.34.1
>
--
Kees Cook
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