4.9 kernel panic in netlink unicast because audit replace passing audit sock as NULL

[Kassey Li]

hi, Paul:

it is hard to running on upstream kernel on my hardware.
I checked the kernel log that we can see  that we are trying to send the sock to task 20802, but it was killed already.
is there any suggest that we can pick up some patches to backport to 4.9 to try ?

[16222.577350] [2018:10:09 23:06:41]init: Service 'logd' (pid 20802) killed by signal 11
[16237.397867] [2018:10:09 23:06:55]audit: netlink_unicast sending to audit_pid=20802 returned error: -111


-000|netlink_unicast(
    |    [X20] ssk = 0x0,
    |    [X21] skb = 0xFFFFFFC0989D5600,
    |    [X24] portid = 20802,
    |    [X19] nonblock = 0)




Kassey Li


________________________________
From: Paul Moore <paul at paul-moore.com>
Sent: October 12, 2018 12:15 PM
To: Kassey Li; Linux-audit at redhat.com
Subject: Re: 4.9 kernel panic in netlink unicast because audit replace passing audit sock as NULL

On October 11, 2018 10:44:01 PM Kassey Li <kasseyli at outlook.com> wrote:
> hi, Paul:
>    we got one kernel panic on 4.9 kernel
>
>                [16237.397896] [2018:10:09 23:06:55]audit: audit_pid=20802 reset
>                [16238.098916] [2018:10:09 23:06:57]Unable to handle kernel NULL pointer dereference at virtual address 00000280
>
>                audit_sock is set to NULL in kauditd_send_skb, but later we are access it again in audit_replace caused this panic.
>                is there patch for such SW issue on 4.9 kernel ?
>
>    static int audit_replace(pid_t pid)
> {
> struct sk_buff *skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0,
>      &pid, sizeof(pid));
>
> if (!skb)
> return -ENOMEM;
> return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
> }

Hi.

Have you been able to reproduce this problem on a recent kernel?  Unfortunately there have been some major changes to that area of the code since v4.9 and it is very likely that we have fixed this issue in the current upstream kernel.

--
paul moore
www.paul-moore.com<http://www.paul-moore.com>



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