linux-kernel - [Patch v3 1/7] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G

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Date:	Sun,  8 Mar 2015 13:38:49 +0800
From:	Baoquan He <bhe@...hat.com>
To:	keescook@...omium.org, yinghai@...nel.org, hpa@...or.com,
	mingo@...hat.com, bp@...e.de, matt.fleming@...el.com,
	vgoyal@...hat.com, tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org, Baoquan He <bhe@...hat.com>
Subject: [Patch v3 1/7] x86, kaslr: Fix a bug that relocation can not be handled when kernel is loaded above 2G

When process 32 bit relocation tables a local variable extended is
defined to calculate the physical address of relocs entry. However
it's type is int which is enough for i386, for x86_64 not enough.
That's why relocation can only be handled when kernel is loaded
below 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 too.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 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 51e9e54..f3ca33e 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -278,7 +278,7 @@ 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;
-- 
1.9.3

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