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Patch "x86/boot: Fix BSS corruption/overwrite bug in early x86 kernel startup" has been added to the 4.10-stable tree

PATCH [email protected] 1 participant 1 message May 16, 2017

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This is a note to let you know that I've just added the patch titled

x86/boot: Fix BSS corruption/overwrite bug in early x86 kernel startup

to the 4.10-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-boot-fix-bss-corruption-overwrite-bug-in-early-x86-kernel-startup.patch
and it can be found in the queue-4.10 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 d594aa0277e541bb997aef0bc0a55172d8138340 Mon Sep 17 00:00:00 2001

From: Ashish Kalra <[email protected]>
Date: Wed, 19 Apr 2017 20:50:15 +0530
Subject: x86/boot: Fix BSS corruption/overwrite bug in early x86 kernel startup

From: Ashish Kalra <[email protected]>

commit d594aa0277e541bb997aef0bc0a55172d8138340 upstream.

The minimum size for a new stack (512 bytes) setup for arch/x86/boot components when the bootloader does not setup/provide a stack for the early boot components is not "enough".

The setup code executing as part of early kernel startup code, uses the stack beyond 512 bytes and accidentally overwrites and corrupts part of the BSS section. This is exposed mostly in the early video setup code, where it was corrupting BSS variables like force_x, force_y, which in-turn affected kernel parameters such as screen_info (screen_info.orig_video_cols) and later caused an exception/panic in console_init().

Most recent boot loaders setup the stack for early boot components, so this stack overwriting into BSS section issue has not been exposed.

Signed-off-by Ashish Kalra <[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 Peter Zijlstra <[email protected]>
Cc Thomas Gleixner <[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/boot/boot.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/boot/boot.h +1 -1
@@ -16,7 +16,7 @@
 #ifndef BOOT_BOOT_H
 #define BOOT_BOOT_H
 
-#define STACK_SIZE	512	/* Minimum number of bytes for stack */
+#define STACK_SIZE	1024	/* Minimum number of bytes for stack */
 
 #ifndef __ASSEMBLY__

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

queue-4.10/x86-boot-fix-bss-corruption-overwrite-bug-in-early-x86-kernel-startup.patch