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-rw-r--r--net_handle_no_dst_on_skb_in_icmp6_send.patch69
1 files changed, 69 insertions, 0 deletions
diff --git a/net_handle_no_dst_on_skb_in_icmp6_send.patch b/net_handle_no_dst_on_skb_in_icmp6_send.patch
new file mode 100644
index 00000000000..3ac7c1039a5
--- /dev/null
+++ b/net_handle_no_dst_on_skb_in_icmp6_send.patch
@@ -0,0 +1,69 @@
+From 79dc7e3f1cd323be4c81aa1a94faa1b3ed987fb2 Mon Sep 17 00:00:00 2001
+From: David Ahern <dsa@cumulusnetworks.com>
+Date: Sun, 27 Nov 2016 18:52:53 -0800
+Subject: [PATCH] net: handle no dst on skb in icmp6_send
+
+Andrey reported the following while fuzzing the kernel with syzkaller:
+
+kasan: CONFIG_KASAN_INLINE enabled
+kasan: GPF could be caused by NULL-ptr deref or user memory access
+general protection fault: 0000 [#1] SMP KASAN
+Modules linked in:
+CPU: 0 PID: 3859 Comm: a.out Not tainted 4.9.0-rc6+ #429
+Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
+task: ffff8800666d4200 task.stack: ffff880067348000
+RIP: 0010:[<ffffffff833617ec>] [<ffffffff833617ec>]
+icmp6_send+0x5fc/0x1e30 net/ipv6/icmp.c:451
+RSP: 0018:ffff88006734f2c0 EFLAGS: 00010206
+RAX: ffff8800666d4200 RBX: 0000000000000000 RCX: 0000000000000000
+RDX: 0000000000000000 RSI: dffffc0000000000 RDI: 0000000000000018
+RBP: ffff88006734f630 R08: ffff880064138418 R09: 0000000000000003
+R10: dffffc0000000000 R11: 0000000000000005 R12: 0000000000000000
+R13: ffffffff84e7e200 R14: ffff880064138484 R15: ffff8800641383c0
+FS: 00007fb3887a07c0(0000) GS:ffff88006cc00000(0000) knlGS:0000000000000000
+CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+CR2: 0000000020000000 CR3: 000000006b040000 CR4: 00000000000006f0
+Stack:
+ ffff8800666d4200 ffff8800666d49f8 ffff8800666d4200 ffffffff84c02460
+ ffff8800666d4a1a 1ffff1000ccdaa2f ffff88006734f498 0000000000000046
+ ffff88006734f440 ffffffff832f4269 ffff880064ba7456 0000000000000000
+Call Trace:
+ [<ffffffff83364ddc>] icmpv6_param_prob+0x2c/0x40 net/ipv6/icmp.c:557
+ [< inline >] ip6_tlvopt_unknown net/ipv6/exthdrs.c:88
+ [<ffffffff83394405>] ip6_parse_tlv+0x555/0x670 net/ipv6/exthdrs.c:157
+ [<ffffffff8339a759>] ipv6_parse_hopopts+0x199/0x460 net/ipv6/exthdrs.c:663
+ [<ffffffff832ee773>] ipv6_rcv+0xfa3/0x1dc0 net/ipv6/ip6_input.c:191
+ ...
+
+icmp6_send / icmpv6_send is invoked for both rx and tx paths. In both
+cases the dst->dev should be preferred for determining the L3 domain
+if the dst has been set on the skb. Fallback to the skb->dev if it has
+not. This covers the case reported here where icmp6_send is invoked on
+Rx before the route lookup.
+
+Fixes: 5d41ce29e ("net: icmp6_send should use dst dev to determine L3 domain")
+Reported-by: Andrey Konovalov <andreyknvl@google.com>
+Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ net/ipv6/icmp.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
+index 7370ad2..2772004 100644
+--- a/net/ipv6/icmp.c
++++ b/net/ipv6/icmp.c
+@@ -447,8 +447,10 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
+
+ if (__ipv6_addr_needs_scope_id(addr_type))
+ iif = skb->dev->ifindex;
+- else
+- iif = l3mdev_master_ifindex(skb_dst(skb)->dev);
++ else {
++ dst = skb_dst(skb);
++ iif = l3mdev_master_ifindex(dst ? dst->dev : skb->dev);
++ }
+
+ /*
+ * Must not send error if the source does not uniquely
+