From: Kees Cook <kees@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
alyssa.milburn@intel.com, scott.d.constable@intel.com,
joao@overdrivepizza.com, andrew.cooper3@citrix.com,
jpoimboe@kernel.org, jose.marchesi@oracle.com,
hjl.tools@gmail.com, ndesaulniers@google.com,
samitolvanen@google.com, nathan@kernel.org, ojeda@kernel.org,
alexei.starovoitov@gmail.com, mhiramat@kernel.org, jmill@asu.edu
Subject: Re: [PATCH v3 09/10] x86/ibt: Implement FineIBT-BHI mitigation
Date: Wed, 19 Feb 2025 10:11:52 -0800 [thread overview]
Message-ID: <202502191008.A13C96E1@keescook> (raw)
In-Reply-To: <20250219163515.259229338@infradead.org>
On Wed, Feb 19, 2025 at 05:21:16PM +0100, Peter Zijlstra wrote:
> While WAIT_FOR_ENDBR is specified to be a full speculation stop; it
> has been shown that some implementations are 'leaky' to such an extend
> that speculation can escape even the FineIBT preamble.
>
> To deal with this, add additional hardening to the FineIBT preamble.
>
> Notably, using a new LLVM feature:
>
> https://github.com/llvm/llvm-project/commit/e223485c9b38a5579991b8cebb6a200153eee245
>
> which encodes the number of arguments in the kCFI preamble's register.
>
> Using this register<->arity mapping, have the FineIBT preamble CALL
> into a stub clobbering the relevant argument registers in the
> speculative case.
>
> (This is where Scott goes and gives more details...)
>
> Suggested-by: Scott Constable <scott.d.constable@intel.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <kees@kernel.org>
--
Kees Cook
next prev parent reply other threads:[~2025-02-19 18:11 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-19 16:21 [PATCH v3 00/10] x86/ibt: FineIBT-BHI Peter Zijlstra
2025-02-19 16:21 ` [PATCH v3 01/10] x86/cfi: Add warn option Peter Zijlstra
2025-02-19 17:50 ` Kees Cook
2025-02-19 17:56 ` Peter Zijlstra
2025-02-19 16:21 ` [PATCH v3 02/10] x86/ibt: Add exact_endbr() helper Peter Zijlstra
2025-02-19 17:51 ` Kees Cook
2025-02-19 16:21 ` [PATCH v3 03/10] x86/traps: Decode 0xEA #UD Peter Zijlstra
2025-02-19 16:47 ` Andrew Cooper
2025-02-19 16:49 ` Peter Zijlstra
2025-02-19 17:52 ` Kees Cook
2025-02-19 16:21 ` [PATCH v3 04/10] x86/traps: Allow custom fixups in handle_bug() Peter Zijlstra
2025-02-19 17:55 ` Kees Cook
2025-02-19 18:17 ` Peter Zijlstra
2025-02-19 16:21 ` [PATCH v3 05/10] x86/ibt: Optimize FineIBT sequence Peter Zijlstra
2025-02-19 17:15 ` Andrew Cooper
2025-02-20 18:28 ` Constable, Scott D
2025-02-19 18:01 ` Kees Cook
2025-02-19 18:18 ` Peter Zijlstra
2025-02-19 18:23 ` Kees Cook
2025-02-19 16:21 ` [PATCH v3 06/10] x86/traps: Decode LOCK Jcc.d8 #UD Peter Zijlstra
2025-02-19 16:45 ` Peter Zijlstra
2025-02-19 18:20 ` Kees Cook
2025-02-19 18:33 ` Peter Zijlstra
2025-02-19 19:44 ` Peter Zijlstra
2025-02-19 16:21 ` [PATCH v3 07/10] x86/ibt: Add paranoid FineIBT mode Peter Zijlstra
2025-02-19 17:31 ` Andrew Cooper
2025-02-19 20:07 ` Peter Zijlstra
2025-02-21 13:40 ` David Laight
2025-02-19 18:05 ` Kees Cook
2025-02-19 16:21 ` [PATCH v3 08/10] x86: BHI stubs Peter Zijlstra
2025-02-19 18:07 ` Kees Cook
2025-02-19 18:07 ` Peter Zijlstra
2025-02-19 16:21 ` [PATCH v3 09/10] x86/ibt: Implement FineIBT-BHI mitigation Peter Zijlstra
2025-02-19 18:11 ` Kees Cook [this message]
2025-02-19 16:21 ` [PATCH v3 10/10] x86/ibt: Optimize fineibt-bhi arity 1 case Peter Zijlstra
2025-02-19 18:21 ` Kees Cook
2025-02-19 17:36 ` [PATCH v3 00/10] x86/ibt: FineIBT-BHI Kees Cook
2025-02-20 11:27 ` Peter Zijlstra
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