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References: <20240202163433.786581-1-abrestic@rivosinc.com> <20240202163433.786581-2-abrestic@rivosinc.com>
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From: Ard Biesheuvel <ardb@kernel.org>
Date: Fri, 2 Feb 2024 17:37:24 +0100
Message-ID: <CAMj1kXGR0thbcDt32pC=KS=tsmSWqQuyhJ2Ftq0vX3u=dLX22g@mail.gmail.com>
Subject: Re: [PATCH 1/2] efi: runtime: Fix potential overflow of soft-reserved
 region size
To: Andrew Bresticker <abrestic@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Albert Ou <aou@eecs.berkeley.edu>, linux-efi@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
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Hi Andrew,

On Fri, 2 Feb 2024 at 17:34, Andrew Bresticker <abrestic@rivosinc.com> wrote:
>
> md_size will have been narrowed if we have >= 4GB worth of pages in a
> soft-reserved region.
>
> Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
> ---
>  drivers/firmware/efi/arm-runtime.c   | 2 +-
>  drivers/firmware/efi/riscv-runtime.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> index 83f5bb57fa4c..f369256c7003 100644
> --- a/drivers/firmware/efi/arm-runtime.c
> +++ b/drivers/firmware/efi/arm-runtime.c
> @@ -107,7 +107,7 @@ static int __init arm_enable_runtime_services(void)
>                 efi_memory_desc_t *md;
>
>                 for_each_efi_memory_desc(md) {
> -                       int md_size = md->num_pages << EFI_PAGE_SHIFT;
> +                       unsigned long md_size = md->num_pages << EFI_PAGE_SHIFT;

Better use u64 here, and below as well.


>                         struct resource *res;
>
>                         if (!(md->attribute & EFI_MEMORY_SP))
> diff --git a/drivers/firmware/efi/riscv-runtime.c b/drivers/firmware/efi/riscv-runtime.c
> index 09525fb5c240..9da79b8169d2 100644
> --- a/drivers/firmware/efi/riscv-runtime.c
> +++ b/drivers/firmware/efi/riscv-runtime.c
> @@ -85,7 +85,7 @@ static int __init riscv_enable_runtime_services(void)
>                 efi_memory_desc_t *md;
>
>                 for_each_efi_memory_desc(md) {
> -                       int md_size = md->num_pages << EFI_PAGE_SHIFT;
> +                       unsigned long md_size = md->num_pages << EFI_PAGE_SHIFT;
>                         struct resource *res;
>
>                         if (!(md->attribute & EFI_MEMORY_SP))
> --
> 2.34.1
>
>