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authorKees Cook <keescook@chromium.org>2015-01-15 16:51:46 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-01-29 17:40:45 -0800
commitc546e47591d7c8b4fa3dc2d9dae14c127f0c3b22 (patch)
tree3463f3ea29df2e10fbc18847aea551cbb6f31186
parent056ad39c15c36bc5ce8ede2ae4db45b44181a6d4 (diff)
x86, boot: Skip relocs when load address unchanged
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@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> Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 30dd59a9f0b4..0c33a7c67ea5 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -361,6 +361,8 @@ 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);
@@ -409,7 +411,12 @@ 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;
}