[PATCH] kaslr: check if kernel location is changed

[Baoquan He]

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
 arch/x86/boot/compressed/misc.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 57ab74d..887f404 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -230,8 +230,9 @@ static void error(char *x)
 		asm("hlt");
 }
 
-#if CONFIG_X86_NEED_RELOCS
-static void handle_relocations(void *output, unsigned long output_len)
+#ifdef CONFIG_X86_NEED_RELOCS
+static void handle_relocations(void *output_orig, void *output,
+			       unsigned long output_len)
 {
 	int *reloc;
 	unsigned long delta, map, ptr;
@@ -242,6 +243,9 @@ static void handle_relocations(void *output, unsigned long output_len)
 	 * Calculate the delta between where vmlinux was linked to load
 	 * and where it was actually loaded.
 	 */
+	if (output_orig == output)
+		return;
+
 	delta = min_addr - LOAD_PHYSICAL_ADDR;
 	if (!delta) {
 		debug_putstr("No relocation needed... ");
@@ -299,7 +303,8 @@ static void handle_relocations(void *output, unsigned long output_len)
 #endif
 }
 #else
-static inline void handle_relocations(void *output, unsigned long output_len)
+static inline void handle_relocations(void *output_orig, void *output,
+				      unsigned long output_len)
 { }
 #endif
 
@@ -360,6 +365,8 @@ asmlinkage __visible 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);
@@ -402,7 +409,7 @@ 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);
+	handle_relocations(output_orig, output, output_len);
 	debug_putstr("done.\nBooting the kernel.\n");
 	return output;
 }
-- 
1.8.5.3

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