xfrm: policy: check policy direction value (CVE-2017-11600)

debian/changelog

@@ -29,6 +29,7 @@ linux (4.12.6-1) UNRELEASED; urgency=medium
   * [i386] perf tools: Fix unwind build (fixes FTBFS)
   * debian/control: Fix version in dependencies on arch-independent
     linux-headers-*-common* (Closes: #869511)
+  * xfrm: policy: check policy direction value (CVE-2017-11600)
 
   [ Salvatore Bonaccorso ]
   * packet: fix tp_reserve race in packet_set_ring (CVE-2017-1000111)

debian/patches/bugfix/all/xfrm-policy-check-policy-direction-value.patch

@@ -0,0 +1,40 @@
+From: Vladis Dronov <vdronov@redhat.com>
+Date: Wed, 2 Aug 2017 19:50:14 +0200
+Subject: xfrm: policy: check policy direction value
+Origin: https://git.kernel.org/linus/7bab09631c2a303f87a7eb7e3d69e888673b9b7e
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-11600
+
+The 'dir' parameter in xfrm_migrate() is a user-controlled byte which is used
+as an array index. This can lead to an out-of-bound access, kernel lockup and
+DoS. Add a check for the 'dir' value.
+
+This fixes CVE-2017-11600.
+
+References: https://bugzilla.redhat.com/show_bug.cgi?id=1474928
+Fixes: 80c9abaabf42 ("[XFRM]: Extension for dynamic update of endpoint address(es)")
+Cc: <stable@vger.kernel.org> # v2.6.21-rc1
+Reported-by: "bo Zhang" <zhangbo5891001@gmail.com>
+Signed-off-by: Vladis Dronov <vdronov@redhat.com>
+Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
+---
+ net/xfrm/xfrm_policy.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+--- a/net/xfrm/xfrm_policy.c
++++ b/net/xfrm/xfrm_policy.c
+@@ -3301,9 +3301,15 @@ int xfrm_migrate(const struct xfrm_selec
+ 	struct xfrm_state *x_new[XFRM_MAX_DEPTH];
+ 	struct xfrm_migrate *mp;
+ 
++	/* Stage 0 - sanity checks */
+ 	if ((err = xfrm_migrate_check(m, num_migrate)) < 0)
+ 		goto out;
+ 
++	if (dir >= XFRM_POLICY_MAX) {
++		err = -EINVAL;
++		goto out;
++	}
++
+ 	/* Stage 1 - find policy */
+ 	if ((pol = xfrm_migrate_policy_find(sel, dir, type, net)) == NULL) {
+ 		err = -ENOENT;

debian/patches/series

@@ -121,6 +121,7 @@ features/all/lockdown/arm64-add-kernel-config-option-to-lock-down-when.patch
 debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
 bugfix/all/packet-fix-tp_reserve-race-in-packet_set_ring.patch
 bugfix/all/udp-consistently-apply-ufo-or-fragmentation.patch
+bugfix/all/xfrm-policy-check-policy-direction-value.patch
 
 # Fix exported symbol versions
 bugfix/alpha/alpha-restore-symbol-versions-for-symbols-exported-f.patch