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    Subject[PATCH 4.14 015/114] ipv6: fix cleanup ordering for ip6_mr failure
    Date
    From: Sabrina Dubroca <sd@queasysnail.net>

    commit afe49de44c27a89e8e9631c44b5ffadf6ace65e2 upstream.

    Commit 15e668070a64 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
    moved the cleanup label for ipmr_fail, but should have changed the
    contents of the cleanup labels as well. Now we can end up cleaning up
    icmpv6 even though it hasn't been initialized (jump to icmp_fail or
    ipmr_fail).

    Simply undo things in the reverse order of their initialization.

    Example of panic (triggered by faking a failure of icmpv6_init):

    kasan: GPF could be caused by NULL-ptr deref or user memory access
    general protection fault: 0000 [#1] PREEMPT SMP KASAN PTI
    [...]
    RIP: 0010:__list_del_entry_valid+0x79/0x160
    [...]
    Call Trace:
    ? lock_release+0x8a0/0x8a0
    unregister_pernet_operations+0xd4/0x560
    ? ops_free_list+0x480/0x480
    ? down_write+0x91/0x130
    ? unregister_pernet_subsys+0x15/0x30
    ? down_read+0x1b0/0x1b0
    ? up_read+0x110/0x110
    ? kmem_cache_create_usercopy+0x1b4/0x240
    unregister_pernet_subsys+0x1d/0x30
    icmpv6_cleanup+0x1d/0x30
    inet6_init+0x1b5/0x23f

    Fixes: 15e668070a64 ("ipv6: reorder icmpv6_init() and ip6_mr_init()")
    Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Cc: Guenter Roeck <linux@roeck-us.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/ipv6/af_inet6.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    --- a/net/ipv6/af_inet6.c
    +++ b/net/ipv6/af_inet6.c
    @@ -1088,11 +1088,11 @@ netfilter_fail:
    igmp_fail:
    ndisc_cleanup();
    ndisc_fail:
    - ip6_mr_cleanup();
    + icmpv6_cleanup();
    icmp_fail:
    - unregister_pernet_subsys(&inet6_net_ops);
    + ip6_mr_cleanup();
    ipmr_fail:
    - icmpv6_cleanup();
    + unregister_pernet_subsys(&inet6_net_ops);
    register_pernet_fail:
    sock_unregister(PF_INET6);
    rtnl_unregister_all(PF_INET6);

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