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