[LTP] [PATCH v2 4/4] Add test for CVE 2020-29373

[Petr Vorel]

Hi Martin,

> Fixes #770

Nice port thanks!

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Few questions below.

...
> +static void run(void)
> +{
> +	uint32_t i, count, tail;
> +	int beef_found = 0;
> +	struct io_uring_sqe *sqe_ptr;
> +	const struct io_uring_cqe *cqe_ptr;
> +
> +	SAFE_SOCKETPAIR(AF_UNIX, SOCK_DGRAM, 0, sockpair);
> +	SAFE_SETSOCKOPT_INT(sockpair[0], SOL_SOCKET, SO_SNDBUF,
> +		32+sizeof(buf));
> +	SAFE_FCNTL(sockpair[0], F_SETFL, O_NONBLOCK);
> +
> +	SAFE_IO_URING_INIT(512, &params, &uring);
> +	sqe_ptr = uring.sqr_entries;
> +
> +	/* Add spam requests to force async processing of the real test */
> +	for (i = 0, tail = *uring.sqr_tail; i < 255; i++, tail++, sqe_ptr++) {
> +		memset(sqe_ptr, 0, sizeof(*sqe_ptr));
> +		sqe_ptr->opcode = IORING_OP_SENDMSG;
> +		sqe_ptr->flags = IOSQE_IO_DRAIN;
> +		sqe_ptr->fd = sockpair[0];
> +		sqe_ptr->addr = (__u64)&spam_header;
> +		sqe_ptr->user_data = SPAM_MARK;
Interesting, original reproducer uses here i

> +		uring.sqr_array[tail & *uring.sqr_mask] = i;
> +	}
> +
> +	/* Add the real test to queue */
> +	memset(sqe_ptr, 0, sizeof(*sqe_ptr));
> +	sqe_ptr->opcode = IORING_OP_SENDMSG;
> +	sqe_ptr->flags = IOSQE_IO_DRAIN;
> +	sqe_ptr->fd = sendsock;
> +	sqe_ptr->addr = (__u64)&beef_header;
> +	sqe_ptr->user_data = BEEF_MARK;
and here also 255, you use much higher 0xbeef.

You probably have a good reason to use here 0xfa7 (higher value). But maybe
explaining why?

> +	uring.sqr_array[tail & *uring.sqr_mask] = i;
> +	count = ++i;
> +	tail++;
> +
> +	__atomic_store(uring.sqr_tail, &tail, __ATOMIC_RELEASE);
> +	SAFE_IO_URING_ENTER(1, uring.fd, count, count, IORING_ENTER_GETEVENTS,
> +		NULL);
> +
> +	/* Check test results */
> +	__atomic_load(uring.cqr_tail, &tail, __ATOMIC_ACQUIRE);
> +
> +	for (i = *uring.cqr_head; i != tail; i++, count--) {
> +		cqe_ptr = uring.cqr_entries + (i & *uring.cqr_mask);
> +		TST_ERR = -cqe_ptr->res;
> +
> +		if (cqe_ptr->user_data == SPAM_MARK) {
> +			if (cqe_ptr->res >= 0 || cqe_ptr->res == -EAGAIN)
> +				continue;
> +
> +			tst_res(TFAIL | TTERRNO,
> +				"Spam request failed unexpectedly");
I'm sorry, I'm lost to which TEST*() call this TTERRNO refers (there are mostly
SAFE_*() macros.
> +			continue;
> +		}
> +
> +		if (cqe_ptr->user_data != BEEF_MARK) {
> +			tst_res(TFAIL, "Unexpected entry in completion queue");
> +			count++;
> +			continue;
> +		}
> +
> +		beef_found = 1;
> +
> +		if (cqe_ptr->res >= 0) {
> +			tst_res(TFAIL, "Write outside chroot succeeded.");
> +		} else if (cqe_ptr->res != -ENOENT) {
> +			tst_res(TFAIL | TTERRNO,
And here.

> +				"Write outside chroot failed unexpectedly");
> +		} else {
> +			tst_res(TPASS,
> +				"Write outside chroot failed as expected");
> +		}
> +	}
> +
> +	__atomic_store(uring.cqr_head, &i, __ATOMIC_RELEASE);
> +
> +	if (!beef_found)
> +		tst_res(TFAIL, "Write outside chroot result not found");
> +
> +	if (count)
> +		tst_res(TFAIL, "Wrong number of entries in completion queue");
> +
> +	/* iteration cleanup */
> +	SAFE_IO_URING_CLOSE(&uring);
> +	SAFE_CLOSE(sockpair[0]);
> +	SAFE_CLOSE(sockpair[1]);
> +}

Kind regards,
Petr