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Subject[PATCH] [STABLE backport 4.9] arm64, vdso: Define vdso_{start,end} as array
Date
From: Kees Cook <keescook@chromium.org>

Commit dbbb08f500d6146398b794fdc68a8e811366b451 upstream.

Adjust vdso_{start|end} to be char arrays to avoid compile-time analysis
that flags "too large" memcmp() calls with CONFIG_FORTIFY_SOURCE.

Cc: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Backported to 4.4, which predates the rework from
2077be6783b5 ("arm64: Use __pa_symbol for kernel symbols") and
5a9e3e156ec1 ("arm64: apply __ro_after_init to some objects")
---
arch/arm64/kernel/vdso.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 97bc68f4c689..908bc5ab94c1 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -36,7 +36,7 @@
#include <asm/vdso.h>
#include <asm/vdso_datapage.h>

-extern char vdso_start, vdso_end;
+extern char vdso_start[], vdso_end[];
static unsigned long vdso_pages;
static struct page **vdso_pagelist;

@@ -115,14 +115,14 @@ static int __init vdso_init(void)
{
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 -EINVAL;
}

- vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
+ vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
- vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
+ vdso_pages + 1, vdso_pages, vdso_start, 1L, vdso_data);

/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
@@ -135,7 +135,7 @@ static int __init vdso_init(void)

/* Grab the vDSO code pages. */
for (i = 0; i < vdso_pages; i++)
- vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE);
+ vdso_pagelist[i + 1] = virt_to_page(vdso_start + i * PAGE_SIZE);

/* Populate the special mapping structures */
vdso_spec[0] = (struct vm_special_mapping) {
--
2.20.0
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