On Sun, Mar 5, 2017 at 9:34 PM, Cong Wang wrote:
> Andrey reported the following kernel crash:
>
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: [#1] SMP KASAN
> Dumping ftrace buffer:
>(ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 14446 Comm: syz-executor6 Not tainted 4.10.0+ #82
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> task: 88001f311700 task.stack: 88001f6e8000
> RIP: 0010:ip6mr_sk_done+0x15a/0x3d0 net/ipv6/ip6mr.c:1618
> RSP: 0018:88001f6ef418 EFLAGS: 00010202
> RAX: dc00 RBX: 110003edde8c RCX: c900043ee000
> RDX: 0004 RSI: 83e3b3f8 RDI: 0020
> RBP: 88001f6ef508 R08: fbfff0dcc5d8 R09:
> R10: 86e62ec0 R11: R12:
> R13: R14: 88001f6ef4e0 R15: 8800380a0040
> FS: 7f7a52cec700() GS:88003ec0() knlGS:
> CS: 0010 DS: ES: CR0: 80050033
> CR2: 0061c500 CR3: 1f1ae000 CR4: 06f0
> DR0: 2000 DR1: 2000 DR2:
> DR3: DR6: 0ff0 DR7: 0600
> Call Trace:
> rawv6_close+0x4c/0x80 net/ipv6/raw.c:1217
> inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425
> inet6_release+0x50/0x70 net/ipv6/af_inet6.c:432
> sock_release+0x8d/0x1e0 net/socket.c:597
> __sock_create+0x39d/0x880 net/socket.c:1226
> sock_create_kern+0x3f/0x50 net/socket.c:1243
> inet_ctl_sock_create+0xbb/0x280 net/ipv4/af_inet.c:1526
> icmpv6_sk_init+0x163/0x500 net/ipv6/icmp.c:954
> ops_init+0x10a/0x550 net/core/net_namespace.c:115
> setup_net+0x261/0x660 net/core/net_namespace.c:291
> copy_net_ns+0x27e/0x540 net/core/net_namespace.c:396
> 9pnet_virtio: no channels available for device ./file1
> create_new_namespaces+0x437/0x9b0 kernel/nsproxy.c:106
> unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:205
> SYSC_unshare kernel/fork.c:2281 [inline]
> SyS_unshare+0x64e/0x1000 kernel/fork.c:2231
> entry_SYSCALL_64_fastpath+0x1f/0xc2
>
> This is because net->ipv6.mr6_tables is not initialized at that point,
> ip6mr_rules_init() is not called yet, therefore on the error path when
> we iterator the list, we trigger this oops. Fix this by reordering
> ip6mr_rules_init() before icmpv6_sk_init().
>
> Reported-by: Andrey Konovalov
> Signed-off-by: Cong Wang
> ---
> net/ipv6/af_inet6.c | 10 +-
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
> index 04db406..a9a9553 100644
> --- a/net/ipv6/af_inet6.c
> +++ b/net/ipv6/af_inet6.c
> @@ -920,12 +920,12 @@ static int __init inet6_init(void)
> err = register_pernet_subsys(&inet6_net_ops);
> if (err)
> goto register_pernet_fail;
> - err = icmpv6_init();
> - if (err)
> - goto icmp_fail;
> err = ip6_mr_init();
> if (err)
> goto ipmr_fail;
> + err = icmpv6_init();
> + if (err)
> + goto icmp_fail;
> err = ndisc_init();
> if (err)
> goto ndisc_fail;
> @@ -1061,10 +1061,10 @@ static int __init inet6_init(void)
> ndisc_cleanup();
> ndisc_fail:
> ip6_mr_cleanup();
> -ipmr_fail:
> - icmpv6_cleanup();
> icmp_fail:
> unregister_pernet_subsys(&inet6_net_ops);
> +ipmr_fail:
> + icmpv6_cleanup();
> register_pernet_fail:
> sock_unregister(PF_INET6);
> rtnl_unregister_all(PF_INET6);
> --
> 2.5.5
>
Thanks!
