ARM: 8748/1: mm: Define vdso_start, vdso_end as array

[ Upstream commit 73b9160d0dfe44dfdaffd6465dc1224c38a4a73c ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h
index 9c99e81..5b85889 100644 (file)
--- 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 a4d6dc0..f4dd7f9 100644 (file)
--- 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;
 }