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

From	Baoquan He <bhe@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH v4 02/20] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G
Date	2016-03-22 08:40 +0100
Message-ID	<rfp4Z-1bB-3@gated-at.bofh.it> (permalink)
References	<rfp4Z-1bB-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
 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;
-- 
2.5.0

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[PATCH v4 02/20] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G Baoquan He <bhe@redhat.com> - 2016-03-22 08:40 +0100

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