[PATCH] ARM64/ACPI: Fix BAD_MADT_GICC_ENTRY() macro implementation

[Will Deacon]

On Fri, May 26, 2017 at 05:40:02PM +0100, Lorenzo Pieralisi wrote:
> The BAD_MADT_GICC_ENTRY() macro checks if a GICC MADT entry passes
> muster from an ACPI specification standpoint. Current macro detects the
> MADT GICC entry length through ACPI firmware version (it changed from 76
> to 80 bytes in the transition from ACPI 5.1 to ACPI 6.0 specification)
> but always uses (erroneously) the ACPICA (latest) struct (ie struct
> acpi_madt_generic_interrupt - that is 80-bytes long) length to check if
> the current GICC entry memory record exceeds the MADT table end in
> memory as defined by the MADT table header itself, which may result in
> false negatives depending on the ACPI firmware version and how the MADT
> entries are laid out in memory (ie on ACPI 5.1 firmware MADT GICC
> entries are 76 bytes long, so by adding 80 to a GICC entry start address
> in memory the resulting address may well be past the actual MADT end,
> triggering a false negative).
> 
> Fix the BAD_MADT_GICC_ENTRY() macro by reshuffling the condition checks
> and update them to always use the firmware version specific MADT GICC
> entry length in order to carry out boundary checks.
> 
> Fixes: b6cfb277378e ("ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro")
> Reported-by: Julien Grall <julien.grall at arm.com>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Julien Grall <julien.grall at arm.com>
> Cc: Hanjun Guo <hanjun.guo at linaro.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Al Stone <ahs3 at redhat.com>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> ---
>  arch/arm64/include/asm/acpi.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Oh, nasty:

Acked-by: Will Deacon <will.deacon at arm.com>

I'm assuming Catalin will pick this up as a fix.

Will

> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 0e99978..59cca1d 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -23,9 +23,9 @@
>  #define ACPI_MADT_GICC_LENGTH	\
>  	(acpi_gbl_FADT.header.revision < 6 ? 76 : 80)
>  
> -#define BAD_MADT_GICC_ENTRY(entry, end)						\
> -	(!(entry) || (unsigned long)(entry) + sizeof(*(entry)) > (end) ||	\
> -	 (entry)->header.length != ACPI_MADT_GICC_LENGTH)
> +#define BAD_MADT_GICC_ENTRY(entry, end)					\
> +	(!(entry) || (entry)->header.length != ACPI_MADT_GICC_LENGTH ||	\
> +	(unsigned long)(entry) + ACPI_MADT_GICC_LENGTH > (end))
>  
>  /* Basic configuration for ACPI */
>  #ifdef	CONFIG_ACPI
> -- 
> 2.10.0
>