Kernel oops+crash on repeated auditd restarts

[Eric Paris]

On Fri, 2012-04-20 at 23:14 -0300, Marcelo Cerri wrote:

> The patch below increments the reference count of a mark when it is
> added to the destroy list. It seems to solve the issue and it doesn't
> seem to cause any memory leak. Please, can you make some tests in your
> environments and let me know if there is any problem with this patch.

That is almost certainly the wrong thing to do.  This test program
should show a memory leak with your patch.  If it doesn't show a memory
leak then something is screwed up in inotify as well.

#include <errno.h>
#include <unistd.h>
#include <sys/inotify.h>

int main(void)
{
	int fd;
	int rc;
	struct inotify_event event[10];

	fd = inotify_init();
	if (fd < 0)
		return errno;

	while(1) {
		rc = inotify_add_watch(fd, "/tmp", IN_CLOSE_WRITE);
		if (rc < 0)
			return errno;
	
		rc = inotify_rm_watch(fd, rc);
		if (rc)
			return errno;
	
		rc = read(fd, event, sizeof(event));
		if (rc < 0)
			return errno;
	}

	return 0;
}

The lifetime of an object is supposed to be from fsnotify_init_mark()
until it's matching reference is dropped in fsnotify_mark_destroy().  It
sounds to me like we are calling put somewhere in the audit code when we
didn't previously call a get....