Commit 6044d159 authored Apr 20, 2022 by Michael Roth Committed by Borislav Petkov Apr 20, 2022

x86/boot: Put globals that are accessed early into the .data section



The helpers in arch/x86/boot/compressed/efi.c might be used during
early boot to access the EFI system/config tables, and in some cases
these EFI helpers might attempt to print debug/error messages, before
console_init() has been called.

__putstr() checks some variables to avoid printing anything before
the console has been initialized, but this isn't enough since those
variables live in .bss, which may not have been cleared yet. This can
lead to a triple-fault occurring, primarily when booting in legacy/CSM
mode (where EFI helpers will attempt to print some debug messages).

Fix this by declaring these globals in .data section instead so there
is no dependency on .bss being cleared before accessing them.

Fixes: c01fce9c ("x86/compressed: Add SEV-SNP feature detection/setup")
Reported-by: Borislav Petkov <bp@suse.de>
Suggested-by: Thomas Lendacky <Thomas.Lendacky@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220420152613.145077-1-michael.roth@amd.com

parent 5dc91f2d

arch/x86/boot/compressed/early_serial_console.c

+2 −1

Original line number	Diff line number	Diff line
		#include "misc.h"

		int early_serial_base;
		/* This might be accessed before .bss is cleared, so use .data instead. */
		int early_serial_base __section(".data");

		#include "../early_serial_console.c"

arch/x86/boot/compressed/misc.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -53,7 +53,10 @@ memptr free_mem_end_ptr;

		static char *vidmem;
		static int vidport;
		static int lines, cols;

		/* These might be accessed before .bss is cleared, so use .data instead. */
		static int lines __section(".data");
		static int cols __section(".data");

		#ifdef CONFIG_KERNEL_GZIP
		#include "../../../../lib/decompress_inflate.c"