arm64, vdso: Define vdso_{start,end} as array

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[sw0312.kim: cherry-pick from stable linux-4.4.y commit c0309c7835cd for gcc 9 build]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: Ibfe172ae0aaa6a308d562339aeabb74a50258874

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 97bc68f4c689f28eac7188f5e0b792b5293c37da..908bc5ab94c11db39630f6e99ca8a262e2df4951 100644 (file)
--- 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) {