| From | Kamal Mostafa <> | Subject | [PATCH 3.13.y-ckt 094/103] x86, boot: Skip relocs when load address unchanged | Date | Wed, 18 Feb 2015 16:33:01 -0800 |
| |
3.13.11-ckt16 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
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: Kamal Mostafa <kamal@canonical.com> --- arch/x86/boot/compressed/misc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 434f077..1b05afd 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -401,6 +401,8 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, unsigned char *output, unsigned long output_len) { + unsigned char *output_orig = output; + real_mode = rmode; sanitize_boot_params(real_mode); @@ -439,7 +441,12 @@ asmlinkage 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; } -- 1.9.1
|