This is a note to let you know that I've just added the patch titled
x86, boot: Skip relocs when load address unchanged
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-skip-relocs-when-load-address-unchanged.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 f285f4a21c3253887caceed493089ece17579d59 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Thu, 15 Jan 2015 16:51:46 -0800
Subject: x86, boot: Skip relocs when load address unchanged
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit f285f4a21c3253887caceed493089ece17579d59 upstream.
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: Baoquan He <bhe@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Tested-by: Thomas D. <whissi@xxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Junjie Mao <eternal.n08@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20150116005146.GA4212@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/compressed/misc.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -361,6 +361,8 @@ asmlinkage __visible void *decompress_ke
unsigned long output_len,
unsigned long run_size)
{
+ unsigned char *output_orig = output;
+
real_mode = rmode;
sanitize_boot_params(real_mode);
@@ -409,7 +411,12 @@ asmlinkage __visible void *decompress_ke
debug_putstr("\nDecompressing Linux... ");
decompress(input_data, input_len, NULL, NULL, output, NULL, error);
parse_elf(output);
- handle_relocations(output, output_len);
+ /*
+ * 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;
}
Patches currently in stable-queue which might be from keescook@xxxxxxxxxxxx are
queue-3.18/x86-boot-skip-relocs-when-load-address-unchanged.patch
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