From: David Ahern dsa@cumulusnetworks.com
commit 79dc7e3f1cd323be4c81aa1a94faa1b3ed987fb2 upstream.
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 Signed-off-by: Nobuhiro Iwamatsu (CIP) nobuhiro1.iwamatsu@toshiba.co.jp Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/ipv6/icmp.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -445,8 +445,10 @@ static void icmp6_send(struct sk_buff *s
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