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Patch "x86/microcode/AMD: Fix more fallout from CONFIG_RANDOMIZE_MEMORY=y" has been added to the 4.8-stable tree

DISCUSSION [email protected] 1 participant 1 message Nov 7, 2016

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Stable branch Memory management x86 x86 microcode update support
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This is a note to let you know that I've just added the patch titled

x86/microcode/AMD: Fix more fallout from CONFIG_RANDOMIZE_MEMORY=y

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-microcode-amd-fix-more-fallout-from-config_randomize_memory-y.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 1c27f646b18fb56308dff82784ca61951bad0b48 Mon Sep 17 00:00:00 2001

From: Borislav Petkov <[email protected]>
Date: Thu, 27 Oct 2016 14:36:23 +0200
Subject: x86/microcode/AMD: Fix more fallout from CONFIG_RANDOMIZE_MEMORY=y

From: Borislav Petkov <[email protected]>

commit 1c27f646b18fb56308dff82784ca61951bad0b48 upstream.

We needed the physical address of the container in order to compute the offset within the relocated ramdisk. And we did this by doing __pa() on the virtual address.

However, __pa() does checks whether the physical address is within PAGE_OFFSET and __START_KERNEL_map - see __phys_addr() - which fail if we have CONFIG_RANDOMIZE_MEMORY enabled: we feed a virtual address which *doesn't* have the randomization offset into a function which uses PAGE_OFFSET which *does* have that offset.

This makes this check fire:

	VIRTUAL_BUG_ON((x > y) || !phys_addr_valid(x));
			^^^^^^

due to the randomization offset.

The fix is as simple as using __pa_nodebug() because we do that randomization offset accounting later in that function ourselves.

Reported-by Bob Peterson <[email protected]>
Tested-by Bob Peterson <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
Cc Andreas Gruenbacher <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Andy Lutomirski <[email protected]>
Cc Borislav Petkov <[email protected]>
Cc Brian Gerst <[email protected]>
Cc Denys Vlasenko <[email protected]>
Cc H. Peter Anvin <[email protected]>
Cc Josh Poimboeuf <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Mel Gorman <[email protected]>
Cc Peter Zijlstra <[email protected]>
Cc Steven Whitehouse <[email protected]>
Cc Thomas Gleixner <[email protected]>
Cc linux-mm <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Ingo Molnar <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/x86/kernel/cpu/microcode/amd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/kernel/cpu/microcode/amd.c +1 -1
@@ -429,7 +429,7 @@ int __init save_microcode_in_initrd_amd(
 	 * We need the physical address of the container for both bitness since
 	 * boot_params.hdr.ramdisk_image is a physical address.
 	 */
-	cont    = __pa(container);
+	cont    = __pa_nodebug(container);
 	cont_va = container;
 #endif

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/x86-microcode-amd-fix-more-fallout-from-config_randomize_memory-y.patch

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