From 5702196e7d9d1232c41769e197eb33ba78a9b463 Mon Sep 17 00:00:00 2001 From: Dylan Yudaken Date: Thu, 30 Jun 2022 02:12:22 -0700 Subject: [PATCH] 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: Dylan Yudaken Link: https://lore.kernel.org/r/20220630091231.1456789-4-dylany@fb.com Signed-off-by: Jens Axboe --- io_uring/net.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/io_uring/net.c b/io_uring/net.c index b77bfbf..06eaef9 100644 --- a/io_uring/net.c +++ b/io_uring/net.c @@ -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; - 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 { + 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, -- 2.7.4