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

Petr Vorel
2021-02-05T16:49:32Z

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