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Wed, 28 Feb 2018 06:30:00 -0800 (PST) Date: Wed, 28 Feb 2018 23:29:51 +0900 From: Jinbum Park To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [kernel-hardening] [PATCH 1/2] arm: mm: Define vdso_start, vdso_end as array Message-ID: <20180228142951.GA3136@pjb1027-Latitude-E5410> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180228_063011_072503_331E3FBE X-CRM114-Status: GOOD ( 17.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kstewart@linuxfoundation.org, mark.rutland@arm.com, catalin.marinas@arm.com, keescook@chromium.org, arnd@arndb.de, gregkh@linuxfoundation.org, pombredanne@nexb.co, will.deacon@arm.com, luto@amacapital.net, danielmicay@gmail.com, dsafonov@virtuozzo.com, tglx@linutronix.de Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Signed-off-by: Jinbum Park Acked-by: Kees Cook --- arch/arm/include/asm/vdso.h | 2 -- arch/arm/kernel/vdso.c | 12 +++++++----- 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/arm/include/asm/vdso.h b/arch/arm/include/asm/vdso.h index 9c99e81..5b85889 100644 --- a/arch/arm/include/asm/vdso.h +++ b/arch/arm/include/asm/vdso.h @@ -12,8 +12,6 @@ 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 --- 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; }