[PATCH v4 02/20] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G

From: Baoquan He
Date: Tue Mar 22 2016 - 03:33:00 EST

When process 32 bit relocation tables a local variable 'extended'
is defined to calculate the physical address of relocs entry.
However its type is 'int' which is enough for i386, but not enough
for x86_64. That's why relocation can only be handled under 2G.
Otherwise a overflow will happen and cause system hang.

Here change it to 'long' as 32 bit inverse relocation processing
does, and this change is safe for i386 relocation handling.

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
arch/x86/boot/compressed/misc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index f35ad9e..c4477d5 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -295,7 +295,7 @@ static void handle_relocations(void *output, unsigned long output_len)
* So we work backwards from the end of the decompressed image.
for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
- int extended = *reloc;
+ long extended = *reloc;
extended += map;

ptr = (unsigned long)extended;