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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jisheng Zhang <jszhang@marvell.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Will Deacon <will.deacon@arm.com>,
        Arnd Bergmann <arnd@arndb.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 71/73] arm64, vdso: Define vdso_{start,end} as array
Date:   Mon,  8 Jul 2019 17:13:21 +0200
Message-Id: <20190708150524.993965245@linuxfoundation.org>
In-Reply-To: <20190708150513.136580595@linuxfoundation.org>
References: <20190708150513.136580595@linuxfoundation.org>
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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>
---
 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) {
-- 
2.20.1