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authorKees Cook <keescook@chromium.org>2015-01-15 16:51:46 -0800
committerThomas Gleixner <tglx@linutronix.de>2015-01-20 12:37:23 +0100
commitf285f4a21c3253887caceed493089ece17579d59 (patch)
tree17d7cc4556d5a1b144b49f79064cdfa222789441 /arch
parent8abb850a03a3a8b11a0e92949e5b99d9cc178e35 (diff)
downloadlinux-f285f4a21c3253887caceed493089ece17579d59.tar.gz
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: Baoquan He <bhe@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org> Tested-by: Thomas 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: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/boot/compressed/misc.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index dcc1c536cc2..a950864a64d 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -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);
@@ -421,7 +423,12 @@ 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);
- 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;
}