[PATCH io_uring-7.1 v3 1/6] io_uring/zcrx: reject REG_NODEV with large rx_buf_size

[Pavel Begunkov <asml.silence@gmail.com>]

The copy fallback path doesn't care about the actual niov size and only
uses first PAGE_SIZE bytes, and any additional space will be wasted.
Since ZCRX_REG_NODEV solely relies on the copy path, it doesn't make
sense to support non-standard rx_buf_len. Reject it for now, and
re-enable once improved.

Fixes: c11728021d5cd ("io_uring/zcrx: implement device-less mode for zcrx")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 io_uring/zcrx.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index f94f74d0f566..1ce867c68446 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -449,6 +449,8 @@ static int io_zcrx_create_area(struct io_zcrx_ifq *ifq,
 			return -EINVAL;
 		buf_size_shift = ilog2(reg->rx_buf_len);
 	}
+	if (!ifq->dev && buf_size_shift != PAGE_SHIFT)
+		return -EOPNOTSUPP;
 
 	ret = -ENOMEM;
 	area = kzalloc_obj(*area);
@@ -462,7 +464,7 @@ static int io_zcrx_create_area(struct io_zcrx_ifq *ifq,
 	if (ifq->dev)
 		area->is_mapped = true;
 
-	if (buf_size_shift > io_area_max_shift(&area->mem)) {
+	if (ifq->dev && buf_size_shift > io_area_max_shift(&area->mem)) {
 		ret = -ERANGE;
 		goto err;
 	}
-- 
2.53.0