CVE-2017-5897 ip6_gre: Invalid reads in ip6gre_err (rhbz 1419848 1419851)

ip6_gre-fix-ip6gre_err-invalid-reads.patch

@@ -0,0 +1,91 @@
+From 7892032cfe67f4bde6fc2ee967e45a8fbaf33756 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet@google.com>
+Date: Sat, 4 Feb 2017 23:18:55 -0800
+Subject: ip6_gre: fix ip6gre_err() invalid reads
+
+Andrey Konovalov reported out of bound accesses in ip6gre_err()
+
+If GRE flags contains GRE_KEY, the following expression
+*(((__be32 *)p) + (grehlen / 4) - 1)
+
+accesses data ~40 bytes after the expected point, since
+grehlen includes the size of IPv6 headers.
+
+Let's use a "struct gre_base_hdr *greh" pointer to make this
+code more readable.
+
+p[1] becomes greh->protocol.
+grhlen is the GRE header length.
+
+Fixes: c12b395a4664 ("gre: Support GRE over IPv6")
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Reported-by: Andrey Konovalov <andreyknvl@google.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ net/ipv6/ip6_gre.c | 40 +++++++++++++++++++++-------------------
+ 1 file changed, 21 insertions(+), 19 deletions(-)
+
+diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
+index 5586318..630b73b 100644
+--- a/net/ipv6/ip6_gre.c
++++ b/net/ipv6/ip6_gre.c
+@@ -367,35 +367,37 @@ static void ip6gre_tunnel_uninit(struct net_device *dev)
+ 
+ 
+ static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+-		u8 type, u8 code, int offset, __be32 info)
++		       u8 type, u8 code, int offset, __be32 info)
+ {
+-	const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)skb->data;
+-	__be16 *p = (__be16 *)(skb->data + offset);
+-	int grehlen = offset + 4;
++	const struct gre_base_hdr *greh;
++	const struct ipv6hdr *ipv6h;
++	int grehlen = sizeof(*greh);
+ 	struct ip6_tnl *t;
++	int key_off = 0;
+ 	__be16 flags;
++	__be32 key;
+ 
+-	flags = p[0];
+-	if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
+-		if (flags&(GRE_VERSION|GRE_ROUTING))
+-			return;
+-		if (flags&GRE_KEY) {
+-			grehlen += 4;
+-			if (flags&GRE_CSUM)
+-				grehlen += 4;
+-		}
++	if (!pskb_may_pull(skb, offset + grehlen))
++		return;
++	greh = (const struct gre_base_hdr *)(skb->data + offset);
++	flags = greh->flags;
++	if (flags & (GRE_VERSION | GRE_ROUTING))
++		return;
++	if (flags & GRE_CSUM)
++		grehlen += 4;
++	if (flags & GRE_KEY) {
++		key_off = grehlen + offset;
++		grehlen += 4;
+ 	}
+ 
+-	/* If only 8 bytes returned, keyed message will be dropped here */
+-	if (!pskb_may_pull(skb, grehlen))
++	if (!pskb_may_pull(skb, offset + grehlen))
+ 		return;
+ 	ipv6h = (const struct ipv6hdr *)skb->data;
+-	p = (__be16 *)(skb->data + offset);
++	greh = (const struct gre_base_hdr *)(skb->data + offset);
++	key = key_off ? *(__be32 *)(skb->data + key_off) : 0;
+ 
+ 	t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr,
+-				flags & GRE_KEY ?
+-				*(((__be32 *)p) + (grehlen / 4) - 1) : 0,
+-				p[1]);
++				 key, greh->protocol);
+ 	if (!t)
+ 		return;
+ 
+-- 
+cgit v0.12
+

kernel.spec

@@ -42,7 +42,7 @@ Summary: The Linux kernel
 # For non-released -rc kernels, this will be appended after the rcX and
 # gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
 #
-%global baserelease 1
+%global baserelease 2
 %global fedora_build %{baserelease}
 
 # base_sublevel is the kernel version we're starting with and patching
@@ -125,7 +125,7 @@ Summary: The Linux kernel
 # Set debugbuildsenabled to 1 for production (build separate debug kernels)
 #  and 0 for rawhide (all kernels are debug kernels).
 # See also 'make debug' and 'make release'.
-%define debugbuildsenabled 1
+%define debugbuildsenabled 0
 
 # Want to build a vanilla kernel build without any non-upstream patches?
 %define with_vanilla %{?_with_vanilla: 1} %{?!_with_vanilla: 0}
@@ -599,6 +599,10 @@ Patch853: 0001-Work-around-for-gcc7-and-arm64.patch
 #CVE-2017-2596 rhbz 1417812 1417813
 Patch854: kvm-fix-page-struct-leak-in-handle_vmon.patch
 
+#CVE-2017-5897 rhbz 1419848 1419851
+Patch855: ip6_gre-fix-ip6gre_err-invalid-reads.patch
+
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -2169,6 +2173,10 @@ fi
 #
 #
 %changelog
+* Tue Feb 07 2017 Justin M. Forbes <jforbes@fedoraproject.org> - 4.10.0-0.rc7.git0.2
+- Reenable debugging options.
+- CVE-2017-5897 ip6_gre: Invalid reads in ip6gre_err (rhbz 1419848 1419851)
+
 * Mon Feb 06 2017 Justin M. Forbes <jforbes@fedoraproject.org> - 4.10.0-0.rc7.git0.1
 - Disable debugging options.
 - Linux v4.10-rc7