[apparmor] [PATCH 02/24] apparmor: convert profile lists to RCU based locking

[Seth Arnold]

In the code below, the "if (error) return error;" near the top of the
loop feels a bit out of place -- if one policy loads fine and a second
policy fails the header check, a profile is on the list_head and never
cleaned up. (I mentioned the caller of this function in a different
email -- this is the case I was referring to.)


int aa_unpack(void *udata, size_t size, struct list_head *lh, const char **ns)
{
	struct aa_profile *tmp, *profile = NULL;
	int error;
	struct aa_ext e = {
		.start = udata,
		.end = udata + size,
		.pos = udata,
	};

	*ns = NULL;
	while (e.pos < e.end) {
		error = verify_header(&e, e.pos == e.start, ns);
		if (error)
			return error; /* XXX if the header fails on a
					 second or subsequent profile,
					 we'll leave the list_head
					 intact XXX */

		/* alignment adjust needed by dfa unpack */
		e.adj = (e.pos - e.start) & 7;
		profile = unpack_profile(&e);
		if (IS_ERR(profile)) {
			error = PTR_ERR(profile);
			goto fail;
		}

		error = verify_profile(profile);
		if (error) {
			aa_put_profile(profile);
			goto fail;
		}

		/* transfer refcount to list */
		list_add_tail(&profile->base.list, lh);
	}

	return 0;

fail:
	/*
	 * outside references to the list of profiles are not possible
	 * as they have not been added to the global list yet, so rcu
	 * is not necessary
	 */
	list_for_each_entry_safe(profile, tmp, lh, base.list) {
			list_del_init(&profile->base.list);
			aa_put_profile(profile);
	}

	return error;
}
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