linux-kernel - Re: [PATCH v5 16/16] Revert "x86/lam: Disable ADDRESS

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: <qhnyso6yukxdyox5hkod2yzrgg56vkr7er4howolgat35dvtd4@6qh6f5r425hi>
Date: Mon, 28 Oct 2024 22:41:56 +0200
From: "Kirill A. Shutemov" <kirill@...temov.name>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>, 	Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 "H. Peter Anvin" <hpa@...or.com>, 	Peter Zijlstra <peterz@...radead.org>,
 Ard Biesheuvel <ardb@...nel.org>,
 	"Paul E. McKenney" <paulmck@...nel.org>,
 Josh Poimboeuf <jpoimboe@...nel.org>,
 	Xiongwei Song <xiongwei.song@...driver.com>, Xin Li <xin3.li@...el.com>,
 	"Mike Rapoport (IBM)" <rppt@...nel.org>,
 Brijesh Singh <brijesh.singh@....com>,
 	Michael Roth <michael.roth@....com>, Tony Luck <tony.luck@...el.com>,
 	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Alexey Kardashevskiy <aik@....com>, 	Jonathan Corbet <corbet@....net>,
 Sohil Mehta <sohil.mehta@...el.com>, 	Ingo Molnar <mingo@...nel.org>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 	Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
 Kai Huang <kai.huang@...el.com>, 	Sandipan Das <sandipan.das@....com>,
 Breno Leitao <leitao@...ian.org>,
 	Rick Edgecombe <rick.p.edgecombe@...el.com>,
 Alexei Starovoitov <ast@...nel.org>, 	Hou Tao <houtao1@...wei.com>,
 Juergen Gross <jgross@...e.com>,
 	Vegard Nossum <vegard.nossum@...cle.com>, Kees Cook <kees@...nel.org>,
 Eric Biggers <ebiggers@...gle.com>, 	Jason Gunthorpe <jgg@...pe.ca>,
 "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
 	Andrew Morton <akpm@...ux-foundation.org>,
 Luis Chamberlain <mcgrof@...nel.org>, 	Yuntao Wang <ytcoode@...il.com>,
 Rasmus Villemoes <linux@...musvillemoes.dk>,
 	Christophe Leroy <christophe.leroy@...roup.eu>,
 Tejun Heo <tj@...nel.org>, Changbin Du <changbin.du@...wei.com>,
 	Huang Shijie <shijie@...amperecomputing.com>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 	Namhyung Kim <namhyung@...nel.org>,
 Arnaldo Carvalho de Melo <acme@...hat.com>, 	linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH v5 16/16] Revert "x86/lam: Disable ADDRESS_MASKING in
 most cases"

On Mon, Oct 28, 2024 at 06:08:04PM +0200, Alexander Shishkin wrote:
> This reverts commit 3267cb6d3a174ff83d6287dcd5b0047bbd912452.
> 
> LASS mitigates the Spectre based on LAM (SLAM) [1] and an earlier
> commit made LAM depend on LASS, so we no longer need to disable LAM at
> compile time, so revert the commit that disables LAM.
> 
> [1] https://download.vusec.net/papers/slam_sp24.pdf
> 
> Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> CC: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>

Before re-enabling LAM, you need to uncomment X86_FEATURE_LAM check in
arch/x86/kernel/cpu/common.c introduced in recent 86e6b1547b3d ("x86: fix
user address masking non-canonical speculation issue").

-- 
  Kiryl Shutsemau / Kirill A. Shutemov