Hi, I forgot to add the version to the subject. This is a patch to 4.4.y only. This is not needed for other kernels. Best regards, Nobuhiro > -----Original Message----- > From: Nobuhiro Iwamatsu [mailto:nobuhiro1.iwamatsu@xxxxxxxxxxxxx] > Sent: Wednesday, May 13, 2020 6:05 PM > To: stable@xxxxxxxxxxxxxxx > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>; Andrey Konovalov <andreyknvl@xxxxxxxxxx>; > David S . Miller <davem@xxxxxxxxxxxxx>; iwamatsu nobuhiro(岩松 信洋 □ＳＷＣ◯ＡＣＴ) > <nobuhiro1.iwamatsu@xxxxxxxxxxxxx> > Subject: [PATCH] net: handle no dst on skb in icmp6_send > > From: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx> > > 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@xxxxxxxxxx> > Signed-off-by: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> > Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@xxxxxxxxxxxxx> > --- > 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 d21e81cd6120e..fa96e05cf22be 100644 > --- a/net/ipv6/icmp.c > +++ b/net/ipv6/icmp.c > @@ -445,8 +445,10 @@ 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 > -- > 2.26.0
