linux-cavium: CVE-2017-5970

ipv4: Invalid IP options could cause skb->dst drop

Reference:
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2017-5970

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
Signed-off-by: Adrian Dudau <adrian.dudau@enea.com>

2 files changed, 55 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-cavium/CVE-2017-5970.patch b/recipes-kernel/linux/linux-cavium/CVE-2017-5970.patch
new file mode 100644
index 0000000..ddfcca1
--- /dev/null
+++ b/recipes-kernel/linux/linux-cavium/CVE-2017-5970.patch
@@ -0,0 +1,54 @@
+From f5b54446630a973e1f27b68599366bbd0ac53066 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet@google.com>
+Date: Sat, 4 Feb 2017 11:16:52 -0800
+Subject: [PATCH] ipv4: keep skb->dst around in presence of IP options
+
+[ Upstream commit 34b2cef20f19c87999fff3da4071e66937db9644 ]
+
+Andrey Konovalov got crashes in __ip_options_echo() when a NULL skb->dst
+is accessed.
+
+ipv4_pktinfo_prepare() should not drop the dst if (evil) IP options
+are present.
+
+We could refine the test to the presence of ts_needtime or srr,
+but IP options are not often used, so let's be conservative.
+
+Thanks to syzkaller team for finding this bug.
+
+CVE: CVE-2017-5970
+Upstream-Status: Backport [from kernel.org longterm 4.9.52]
+
+Fixes: d826eb14ecef ("ipv4: PKTINFO doesnt need dst reference")
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Reported-by: Andrey Konovalov <andreyknvl@google.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
+---
+ net/ipv4/ip_sockglue.c | 9 ++++++++-
+ 1 file changed, 8 insertions(+), 1 deletion(-)
+
+diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
+index f226f408..65336f3 100644
+--- a/net/ipv4/ip_sockglue.c
++++ b/net/ipv4/ip_sockglue.c
+@@ -1215,7 +1215,14 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
+                pktinfo->ipi_ifindex = 0;
+                pktinfo->ipi_spec_dst.s_addr = 0;
+        }
+-       skb_dst_drop(skb);
++       /* We need to keep the dst for __ip_options_echo()
++        * We could restrict the test to opt.ts_needtime || opt.srr,
++        * but the following is good enough as IP options are not often used.
++        */
++       if (unlikely(IPCB(skb)->opt.optlen))
++               skb_dst_force(skb);
++       else
++               skb_dst_drop(skb);
+ }
+ 
+ int ip_setsockopt(struct sock *sk, int level,
+-- 
+1.9.1
+
diff --git a/recipes-kernel/linux/linux-cavium_4.9.inc b/recipes-kernel/linux/linux-cavium_4.9.inc
index e35c12f..fc1a341 100644
--- a/recipes-kernel/linux/linux-cavium_4.9.inc
+++ b/recipes-kernel/linux/linux-cavium_4.9.inc
@@ -20,6 +20,7 @@ SRC_URI = "git://git@git.enea.com/linux/linux-cavium.git;protocol=ssh;name=machi
            file://CVE-2017-5551.patch \
            file://CVE-2017-5577.patch \
            file://CVE-2017-5669.patch \
+           file://CVE-2017-5970.patch \
            file://CVE-2017-7487.patch \
            file://CVE-2017-7618.patch \
            file://CVE-2017-7645.patch \