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io_uring: allow iov_len = 0 for recvmsg and buffer select

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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 <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-4-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Dylan Yudaken 2022-06-30 02:12:22 -07:00 committed by Jens Axboe
parent 32f3c434b1
commit 5702196e7d
1 changed files with 11 additions and 5 deletions
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16
io_uring/net.c
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@ -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,