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Subject[PATCH 4.9 220/329] ARM: 8748/1: mm: Define vdso_start, vdso_end as array
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Jinbum Park <jinb.park7@gmail.com>

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

--- a/arch/arm/include/asm/vdso.h
+++ b/arch/arm/include/asm/vdso.h
@@ -11,8 +11,6 @@ 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 */
--- 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;

@@ -179,13 +181,13 @@ 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 *),
@@ -200,7 +202,7 @@ 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;
}

@@ -211,7 +213,7 @@ static int __init vdso_init(void)

cntvct_ok = cntvct_functional();

- patch_vdso(&vdso_start);
+ patch_vdso(vdso_start);

return 0;
}

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