audit,io_uring,io-wq: call __audit_uring_exit for dummy contexts

Not calling the function for dummy contexts will cause the context to
not be reset. During the next syscall, this will cause an error in
__audit_syscall_entry:

	WARN_ON(context->context != AUDIT_CTX_UNUSED);
	WARN_ON(context->name_count);
	if (context->context != AUDIT_CTX_UNUSED || context->name_count) {
		audit_panic("unrecoverable error in audit_syscall_entry()");
		return;
	}

These problematic dummy contexts are created via the following call
chain:

       exit_to_user_mode_prepare
    -> arch_do_signal_or_restart
    -> get_signal
    -> task_work_run
    -> tctx_task_work
    -> io_req_task_submit
    -> io_issue_sqe
    -> audit_uring_entry

Cc: stable@vger.kernel.org
Fixes: 5bd2182d ("audit,io_uring,io-wq: add some basic audit support to io_uring")
Signed-off-by: Julian Orth <ju.orth@gmail.com>
[PM: subject line tweaks]
Signed-off-by: Paul Moore <paul@paul-moore.com>

include/linux/audit.h

@@ -339,7 +339,7 @@ static inline void audit_uring_entry(u8 op)
 }
 static inline void audit_uring_exit(int success, long code)
 {
-	if (unlikely(!audit_dummy_context()))
+	if (unlikely(audit_context()))
 		__audit_uring_exit(success, code);
 }
 static inline void audit_syscall_entry(int major, unsigned long a0,

kernel/auditsc.c

@@ -1959,6 +1959,12 @@ void __audit_uring_exit(int success, long code)
 {
 	struct audit_context *ctx = audit_context();
 
+	if (ctx->dummy) {
+		if (ctx->context != AUDIT_CTX_URING)
+			return;
+		goto out;
+	}
+
 	if (ctx->context == AUDIT_CTX_SYSCALL) {
 		/*
 		 * NOTE: See the note in __audit_uring_entry() about the case