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| author | Kees Cook <keescook@chromium.org> | 2015-01-15 16:51:46 -0800 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-01-29 15:45:05 +0100 |
| commit | 301ca855ac7feea569284adcf3dfe1bd760fe5b7 (patch) | |
| tree | 4dc5311c01e35c6f11a1d7d34285fba11f826e34 | |
| parent | 31f7649d1538ce063cf48af05704ab7b9a0c8fbf (diff) | |
| download | lwn-301ca855ac7feea569284adcf3dfe1bd760fe5b7.tar.gz lwn-301ca855ac7feea569284adcf3dfe1bd760fe5b7.zip | |
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: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | arch/x86/boot/compressed/misc.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 434f077d2c4d..1b05afd8cd7f 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; } |