From 73b9160d0dfe44dfdaffd6465dc1224c38a4a73c Mon Sep 17 00:00:00 2001
From: Jinbum Park <jinb.park7@gmail.com>
Date: Tue, 6 Mar 2018 01:37:21 +0100
Subject: [PATCH] ARM: 8748/1: mm: Define vdso_start, vdso_end as array
Git-commit: 73b9160d0dfe44dfdaffd6465dc1224c38a4a73c
Patch-mainline: v4.16
References: bsc#1051510

Define vdso_start, vdso_end as array to avoid compile-time analysis error
for the case of built with CONFIG_FORTIFY_SOURCE.

and, since vdso_start, vdso_end are used in vdso.c only,
move extern-declaration from vdso.h to vdso.c.

If kernel is built with CONFIG_FORTIFY_SOURCE,
compile-time error happens at this code.
- if (memcmp(&vdso_start, "177ELF", 4))

The size of "&vdso_start" is recognized as 1 byte, but n is 4,
So that compile-time error is reported.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 arch/arm/include/asm/vdso.h |  2 --
 arch/arm/kernel/vdso.c      | 12 +++++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
index 9c99e817535e..5b85889f82ee 100644
--- a/arch/arm/include/asm/vdso.h
+++ b/arch/arm/include/asm/vdso.h
@@ -12,8 +12,6 @@ struct mm_struct;
 
 void arm_install_vdso(struct mm_struct *mm, unsigned long addr);
 
-extern char vdso_start, vdso_end;
-
 extern unsigned int vdso_total_pages;
 
 #else /* CONFIG_VDSO */
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index a4d6dc0f2427..f4dd7f9663c1 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -39,6 +39,8 @@
 
 static struct page **vdso_text_pagelist;
 
+extern char vdso_start[], vdso_end[];
+
 /* Total number of pages needed for the data and text portions of the VDSO. */
 unsigned int vdso_total_pages __ro_after_init;
 
@@ -197,13 +199,13 @@ static int __init vdso_init(void)
 	unsigned int text_pages;
 	int i;
 
-	if (memcmp(&vdso_start, "\177ELF", 4)) {
+	if (memcmp(vdso_start, "\177ELF", 4)) {
 		pr_err("VDSO is not a valid ELF object!\n");
 		return -ENOEXEC;
 	}
 
-	text_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
-	pr_debug("vdso: %i text pages at base %p\n", text_pages, &vdso_start);
+	text_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+	pr_debug("vdso: %i text pages at base %p\n", text_pages, vdso_start);
 
 	/* Allocate the VDSO text pagelist */
 	vdso_text_pagelist = kcalloc(text_pages, sizeof(struct page *),
@@ -218,7 +220,7 @@ static int __init vdso_init(void)
 	for (i = 0; i < text_pages; i++) {
 		struct page *page;
 
-		page = virt_to_page(&vdso_start + i * PAGE_SIZE);
+		page = virt_to_page(vdso_start + i * PAGE_SIZE);
 		vdso_text_pagelist[i] = page;
 	}
 
@@ -229,7 +231,7 @@ static int __init vdso_init(void)
 
 	cntvct_ok = cntvct_functional();
 
-	patch_vdso(&vdso_start);
+	patch_vdso(vdso_start);
 
 	return 0;
 }
-- 
2.18.0