Commit 5702196e authored by Dylan Yudaken's avatar Dylan Yudaken Committed by Jens Axboe
Browse files

io_uring: allow iov_len = 0 for recvmsg and buffer select 



When using BUFFER_SELECT there is no technical requirement that the user
actually provides iov, and this removes one copy_from_user call.

So allow iov_len to be 0.

Signed-off-by: default avatarDylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-4-dylany@fb.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 32f3c434

io_uring/net.c

+11 −5
Original line number Diff line number Diff line
@@ -300,12 +300,18 @@ static int __io_recvmsg_copy_hdr(struct io_kiocb *req, 
		return ret;



	if (req->flags & REQ_F_BUFFER_SELECT) {

		if (iov_len > 1)

		if (iov_len == 0) {

			sr->len = iomsg->fast_iov[0].iov_len = 0;

			iomsg->fast_iov[0].iov_base = NULL;

			iomsg->free_iov = NULL;

		} else if (iov_len > 1) {

			return -EINVAL;

		} else {

			if (copy_from_user(iomsg->fast_iov, uiov, sizeof(*uiov)))

				return -EFAULT;

			sr->len = iomsg->fast_iov[0].iov_len;

			iomsg->free_iov = NULL;

		}

	} else {

		iomsg->free_iov = iomsg->fast_iov;

		ret = __import_iovec(READ, uiov, iov_len, UIO_FASTIOV,