linux-kernel - Re: [PATCH 1/1] riscv: efi: Set NX compat flag in PE/COFF header

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3c2ff70d-a580-4bba-b6e2-1b66b0a98c5d@ghiti.fr>
Date: Tue, 1 Oct 2024 15:51:27 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>
Cc: Ard Biesheuvel <ardb@...nel.org>,
 Emil Renner Berthing <emil.renner.berthing@...onical.com>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH 1/1] riscv: efi: Set NX compat flag in PE/COFF header

Hi Heinrich,

On 29/09/2024 16:02, Heinrich Schuchardt wrote:
> The IMAGE_DLLCHARACTERISTICS_NX_COMPAT informs the firmware that the
> EFI binary does not rely on pages that are both executable and
> writable.
>
> The flag is used by some distro versions of GRUB to decide if the EFI
> binary may be executed.
>
> As the Linux kernel neither has RWX sections nor needs RWX pages for
> relocation we should set the flag.
>
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@...onical.com>
> ---
>   arch/riscv/kernel/efi-header.S | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/efi-header.S b/arch/riscv/kernel/efi-header.S
> index 515b2dfbca75..c5f17c2710b5 100644
> --- a/arch/riscv/kernel/efi-header.S
> +++ b/arch/riscv/kernel/efi-header.S
> @@ -64,7 +64,7 @@ extra_header_fields:
>   	.long	efi_header_end - _start			// SizeOfHeaders
>   	.long	0					// CheckSum
>   	.short	IMAGE_SUBSYSTEM_EFI_APPLICATION		// Subsystem
> -	.short	0					// DllCharacteristics
> +	.short	IMAGE_DLL_CHARACTERISTICS_NX_COMPAT	// DllCharacteristics
>   	.quad	0					// SizeOfStackReserve
>   	.quad	0					// SizeOfStackCommit
>   	.quad	0					// SizeOfHeapReserve


I don't understand if this fixes something or not: what could go wrong 
if we don't do this?

Thanks,

Alex