We do not need to hold the audit_cmd_mutex for this family of cases.  The
possible exception to this is the call to audit_filter_user(), so drop the lock
immediately after.  To help in fixing the race we are trying to avoid, make
sure that nothing called by audit_filter_user() calls audit_log_start().  In
particular, watch out for *_audit_rule_match().

This fix will take care of systemd and anything USING audit.  It still means
that we could race with something configuring audit and auditd shutting down.

Signed-off-by: Richard Guy Briggs <r...@tricolour.ca>
Signed-off-by: Richard Guy Briggs <r...@redhat.com>
---
 kernel/audit.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 4689012..4cbc945 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -713,6 +713,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct 
nlmsghdr *nlh)
                                if (err)
                                        break;
                        }
+                       mutex_unlock(&audit_cmd_mutex);
                        audit_log_common_recv_msg(&ab, msg_type);
                        if (msg_type != AUDIT_USER_TTY)
                                audit_log_format(ab, " msg='%.1024s'",
@@ -729,6 +730,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct 
nlmsghdr *nlh)
                        }
                        audit_set_pid(ab, NETLINK_CB(skb).portid);
                        audit_log_end(ab);
+                       mutex_lock(&audit_cmd_mutex);
                }
                break;
        case AUDIT_ADD_RULE:
-- 
1.7.1

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