linux-kernel - [PATCH 4.8 118/140] arm64: kaslr: fix breakage with CONFIG

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Date:   Wed, 26 Oct 2016 14:22:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Timur Tabi <timur@...eaurora.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Will Deacon <will.deacon@....com>
Subject: [PATCH 4.8 118/140] arm64: kaslr: fix breakage with CONFIG_MODVERSIONS=y

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>

commit 9c0e83c371cf4696926c95f9c8c77cd6ea803426 upstream.

As it turns out, the KASLR code breaks CONFIG_MODVERSIONS, since the
kcrctab has an absolute address field that is relocated at runtime
when the kernel offset is randomized.

This has been fixed already for PowerPC in the past, so simply wire up
the existing code dealing with this issue.

Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR")
Tested-by: Timur Tabi <timur@...eaurora.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/include/asm/module.h |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -17,6 +17,7 @@
 #define __ASM_MODULE_H
 
 #include <asm-generic/module.h>
+#include <asm/memory.h>
 
 #define MODULE_ARCH_VERMAGIC	"aarch64"
 
@@ -32,6 +33,10 @@ u64 module_emit_plt_entry(struct module
 			  Elf64_Sym *sym);
 
 #ifdef CONFIG_RANDOMIZE_BASE
+#ifdef CONFIG_MODVERSIONS
+#define ARCH_RELOCATES_KCRCTAB
+#define reloc_start 		(kimage_vaddr - KIMAGE_VADDR)
+#endif
 extern u64 module_alloc_base;
 #else
 #define module_alloc_base	((u64)_etext - MODULES_VSIZE)