linux-kernel - RE: [PATCH v2 2/6] x86-64: Convert stack protector to normal percpu variable

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: <2c23335e98bc4a66b1fd779a78ddd821@AcuMS.aculab.com>
Date:   Wed, 1 Dec 2021 09:50:57 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Brian Gerst' <brgerst@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
CC:     Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        "Peter Zijlstra" <peterz@...radead.org>
Subject: RE: [PATCH v2 2/6] x86-64: Convert stack protector to normal percpu
 variable

From: Brian Gerst
> Sent: 30 November 2021 20:56
> 
> Older versions of GCC fixed the location of the stack protector canary
> at %gs:40.  This constraint forced the percpu section to be linked at
> virtual address 0 so that the canary could be the first data object in
> the percpu section.  Supporting the zero-based percpu section requires
> additional code to handle relocations for RIP-relative references to
> percpu data, extra complexity to kallsyms, and workarounds for linker
> bugs due to the use of absolute symbols.
> 
> Since version 8.1, GCC has options to configure the location of the
> canary value.  This allows the canary to be turned into a normal
> percpu variable and removes the constraint that the percpu section
> be zero-based.

I didn't think the minimum gcc version has been raised as far as 8.1?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)