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Commit f285f4a2 authored by Kees Cook's avatar Kees Cook Committed by Thomas Gleixner
Browse files

x86, boot: Skip relocs when load address unchanged 



On 64-bit, relocation is not required unless the load address gets
changed. Without this, relocations do unexpected things when the kernel
is above 4G.

Reported-by: default avatarBaoquan He <bhe@redhat.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Tested-by: default avatarThomas D. <whissi@whissi.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8abb850a

arch/x86/boot/compressed/misc.c

+8 −1
Original line number Diff line number Diff line
@@ -373,6 +373,8 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, 
				  unsigned long output_len,

				  unsigned long run_size)

{

	unsigned char *output_orig = output;



	real_mode = rmode;



	sanitize_boot_params(real_mode);
@@ -421,6 +423,11 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, 
	debug_putstr("\nDecompressing Linux... ");

	decompress(input_data, input_len, NULL, NULL, output, NULL, error);

	parse_elf(output);

	/*

	 * 32-bit always performs relocations. 64-bit relocations are only

	 * needed if kASLR has chosen a different load address.

	 */

	if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig)

		handle_relocations(output, output_len);

	debug_putstr("done.\nBooting the kernel.\n");

	return output;