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

[Paul Moore]

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