From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753972AbdDJPSZ (ORCPT ); Mon, 10 Apr 2017 11:18:25 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:51460 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753841AbdDJPSX (ORCPT ); Mon, 10 Apr 2017 11:18:23 -0400 Message-Id: <20170410151723.518412863@linutronix.de> User-Agent: quilt/0.63-1 Date: Mon, 10 Apr 2017 17:14:27 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Peter Zijlstra , Andy Lutomirski , Mathias Krause , Roland McGrath , stable@vger.kernel.org Subject: [patch 1/3] x86/vdso: Ensure vdso32_enabled gets set to valid values only References: <20170410151426.808543816@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86vdso_Ensure_vdso32_enabled_gets_set_to_valid_values_only.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mathias Krause vdso_enabled can be set to arbitrary integer values via the kernel command line 'vdso32=' parameter or via 'sysctl abi.vsyscall32'. load_vdso32() only maps VDSO if vdso_enabled == 1, but ARCH_DLINFO_IA32 merily checks for vdso_enabled != 0. As a consequence the AT_SYSINFO_EHDR auxiliary vector for the VDSO_ENTRY is emitted with a NULL pointer which causes a segfault when the application tries to use the VDSO. Restrict the valid arguments on the command line and the sysctl to 0 and 1. Fixes: b0b49f2673f0 ("x86, vdso: Remove compat vdso support") Signed-off-by: Mathias Krause Acked-by: Andy Lutomirski Cc: Roland McGrath Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1491424561-7187-1-git-send-email-minipli@googlemail.com Signed-off-by: Thomas Gleixner --- arch/x86/entry/vdso/vdso32-setup.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/arch/x86/entry/vdso/vdso32-setup.c +++ b/arch/x86/entry/vdso/vdso32-setup.c @@ -30,8 +30,10 @@ static int __init vdso32_setup(char *s) { vdso32_enabled = simple_strtoul(s, NULL, 0); - if (vdso32_enabled > 1) + if (vdso32_enabled > 1) { pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n"); + vdso32_enabled = 0; + } return 1; } @@ -62,13 +64,18 @@ subsys_initcall(sysenter_setup); /* Register vsyscall32 into the ABI table */ #include +static const int zero; +static const int one = 1; + static struct ctl_table abi_table2[] = { { .procname = "vsyscall32", .data = &vdso32_enabled, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec + .proc_handler = proc_dointvec_minmax, + .extra1 = (int *)&zero, + .extra2 = (int *)&one, }, {} };