FAILED: patch "[PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only" failed to apply to 5.10-stable tree

FAILED: patch "[PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only" failed to apply to 5.10-stable tree

[gregkh]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b648ab487f31bc4c38941bc770ea97fe394304bb Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 23 Jul 2022 17:22:47 +0200
Subject: [PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only

The mitigations for RETBleed are currently ineffective on x86_32 since
entry_32.S does not use the required macros.  However, for an x86_32
target, the kconfig symbols for them are still enabled by default and
/sys/devices/system/cpu/vulnerabilities/retbleed will wrongly report
that mitigations are in place.

Make all of these symbols depend on X86_64, and only enable RETHUNK by
default on X86_64.

Fixes: f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YtwSR3NNsWp1ohfV@decadent.org.uk

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e58798f636d4..1670a3fed263 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2473,7 +2473,7 @@ config RETHUNK
 	bool "Enable return-thunks"
 	depends on RETPOLINE && CC_HAS_RETURN_THUNK
 	select OBJTOOL if HAVE_OBJTOOL
-	default y
+	default y if X86_64
 	help
 	  Compile the kernel with the return-thunks compiler option to guard
 	  against kernel-to-user data leaks by avoiding return speculation.
@@ -2482,21 +2482,21 @@ config RETHUNK
 
 config CPU_UNRET_ENTRY
 	bool "Enable UNRET on kernel entry"
-	depends on CPU_SUP_AMD && RETHUNK
+	depends on CPU_SUP_AMD && RETHUNK && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=unret mitigation.
 
 config CPU_IBPB_ENTRY
 	bool "Enable IBPB on kernel entry"
-	depends on CPU_SUP_AMD
+	depends on CPU_SUP_AMD && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=ibpb mitigation.
 
 config CPU_IBRS_ENTRY
 	bool "Enable IBRS on kernel entry"
-	depends on CPU_SUP_INTEL
+	depends on CPU_SUP_INTEL && X86_64
 	default y
 	help
 	  Compile the kernel with support for the spectre_v2=ibrs mitigation.

Re: FAILED: patch "[PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only" failed to apply to 5.10-stable tree

[Ben Hutchings]

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I'm attaching a backport that should work for all of 5.10, 5.15, and
5.18.

Ben.

-- 
Ben Hutchings
Larkinson's Law: All laws are basically false.

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From 999bc23969f190ec9aa54a0ca20a8c94e2d67ba1 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 23 Jul 2022 17:22:47 +0200
Subject: [PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only

commit b648ab487f31bc4c38941bc770ea97fe394304bb upstream.

The mitigations for RETBleed are currently ineffective on x86_32 since
entry_32.S does not use the required macros.  However, for an x86_32
target, the kconfig symbols for them are still enabled by default and
/sys/devices/system/cpu/vulnerabilities/retbleed will wrongly report
that mitigations are in place.

Make all of these symbols depend on X86_64, and only enable RETHUNK by
default on X86_64.

Fixes: f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YtwSR3NNsWp1ohfV@decadent.org.uk
[bwh: Backported to 5.10/5.15/5.18: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/x86/Kconfig | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4d1d87f76a74..ce1f5a876cfe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2469,7 +2469,7 @@ config RETPOLINE
 config RETHUNK
 	bool "Enable return-thunks"
 	depends on RETPOLINE && CC_HAS_RETURN_THUNK
-	default y
+	default y if X86_64
 	help
 	  Compile the kernel with the return-thunks compiler option to guard
 	  against kernel-to-user data leaks by avoiding return speculation.
@@ -2478,21 +2478,21 @@ config RETHUNK
 
 config CPU_UNRET_ENTRY
 	bool "Enable UNRET on kernel entry"
-	depends on CPU_SUP_AMD && RETHUNK
+	depends on CPU_SUP_AMD && RETHUNK && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=unret mitigation.
 
 config CPU_IBPB_ENTRY
 	bool "Enable IBPB on kernel entry"
-	depends on CPU_SUP_AMD
+	depends on CPU_SUP_AMD && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=ibpb mitigation.
 
 config CPU_IBRS_ENTRY
 	bool "Enable IBRS on kernel entry"
-	depends on CPU_SUP_INTEL
+	depends on CPU_SUP_INTEL && X86_64
 	default y
 	help
 	  Compile the kernel with support for the spectre_v2=ibrs mitigation.

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Re: FAILED: patch "[PATCH] x86/speculation: Make all RETbleed mitigations 64-bit only" failed to apply to 5.10-stable tree

[Greg KH]

On Mon, Aug 01, 2022 at 08:44:35PM +0200, Ben Hutchings wrote:
> 
> I'm attaching a backport that should work for all of 5.10, 5.15, and
> 5.18.

Thanks, now queued up.

greg k-h