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 3.18-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-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d594aa0277e541bb997aef0bc0a55172d8138340 Mon Sep 17 00:00:00 2001 From: Ashish Kalra <ashish@xxxxxxxxxxxxxx> 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 <ashish@xxxxxxxxxxxxxx> 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 <ashish@xxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20170419152015.10011-1-ashishkalra@Ashishs-MacBook-Pro.local Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/boot/boot.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -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 ashish@xxxxxxxxxxxxxx are queue-3.18/x86-boot-fix-bss-corruption-overwrite-bug-in-early-x86-kernel-startup.patch