[PATCH 4.4 08/45] x86/vdso: Ensure vdso32_enabled gets set to valid values only

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 4.4 08/45] x86/vdso: Ensure vdso32_enabled gets set to valid values only
Date	2017-04-19 17:10 +0200
Message-ID	<txZp2-4Zt-79@gated-at.bofh.it> (permalink)
References	<txZfj-4Gn-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Krause <minipli@googlemail.com>

commit c06989da39cdb10604d572c8c7ea8c8c97f3c483 upstream.

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 <minipli@googlemail.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@redhat.com>
Link: http://lkml.kernel.org/r/1491424561-7187-1-git-send-email-minipli@googlemail.com
Link: http://lkml.kernel.org/r/20170410151723.518412863@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -31,8 +31,10 @@ 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;
 }
@@ -63,13 +65,18 @@ subsys_initcall(sysenter_setup);
 /* Register vsyscall32 into the ABI table */
 #include <linux/sysctl.h>
 
+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,
 	},
 	{}
 };

Thread

[PATCH 4.4 00/45] 4.4.63-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:00 +0200
  [PATCH 4.4 44/45] sctp: deny peeloff operation on asocs with threads sleeping on it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:00 +0200
  [PATCH 4.4 32/45] mm: Tighten x86 /dev/mem with zeroing reads Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:00 +0200
  [PATCH 4.4 16/45] xen, fbfront: fix connecting to backend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 15/45] scsi: sd: Fix capacity calculation with 32-bit sector_t Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 27/45] ath9k: fix NULL pointer dereference Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 20/45] char: Drop bogus dependency of DEVPORT on !M68K Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 11/45] iscsi-target: Fix TMR reference leak during session shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 23/45] kvm: fix page struct leak in handle_vmon Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 12/45] iscsi-target: Drop work-around for legacy GlobalSAN initiator Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 10/45] acpi, nfit, libnvdimm: fix interleave set cookie calculation (64-bit comparison) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 14/45] scsi: sd: Consider max_xfer_blocks if opt_xfer_blocks is unusable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 03/45] drm/nouveau/mpeg: mthd returns true on success now Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 06/45] Input: xpad - add support for Razer Wildcat gamepad Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 39/45] catc: Use heap buffer for memory size test Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 25/45] powerpc: Disable HFSCR[TM] if TM is not supported Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 07/45] perf/x86: Avoid exposing wrong/stale data in intel_pmu_lbr_read_32() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 41/45] SUNRPC: fix refcounting problems with auth_gss messages. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 02/45] thp: fix MADV_DONTNEED vs clear soft dirty race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 31/45] rtc: tegra: Implement clock handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 17/45] libnvdimm: fix reconfig_mutex, mmap_sem, and jbd2_handle lockdep splat Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 05/45] CIFS: store results of cifs_reopen_file to avoid infinite wait Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 08/45] x86/vdso: Ensure vdso32_enabled gets set to valid values only Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 40/45] ibmveth: calculate gso_segs for large packets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 21/45] char: lack of bool string made CONFIG_DEVPORT always on Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 42/45] tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 38/45] catc: Combine failure cleanup code in catc_probe() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 26/45] crypto: ahash - Fix EINPROGRESS notification callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  [PATCH 4.4 01/45] cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:10 +0200
  Re: [PATCH 4.4 00/45] 4.4.63-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-04-19 22:40 +0200
  Re: [PATCH 4.4 00/45] 4.4.63-stable review Guenter Roeck <linux@roeck-us.net> - 2017-04-20 01:30 +0200

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