linux-kernel - Re: [PATCH] x86: efi: avoid BUILD_BUG_ON() for non-constant p4d

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: <20210204221318.GI32255@zn.tnic>
Date:   Thu, 4 Feb 2021 23:13:18 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Arnd Bergmann <arnd@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-efi <linux-efi@...r.kernel.org>,
        platform-driver-x86@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH] x86: efi: avoid BUILD_BUG_ON() for non-constant p4d_index

On Thu, Feb 04, 2021 at 04:43:58PM -0500, Arvind Sankar wrote:
> This should check EFI_VA_END instead of EFI_VA_START, and maybe throw in
> a BUG_ON if EFI_VA_END >= EFI_VA_START.

No need:

        if (efi_va < EFI_VA_END) {
                pr_warn(FW_WARN "VA address range overflow!\n");
                return;
        }

We already check we're not going over at map time. And our runtime
services range is hardcoded. And we're switching to that PGD on each
runtime services call.

So I don't see the point for keeping any of the assertions.

Unless you have other valid arguments for keeping them...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette