lib/iov_iter: initialize "flags" in new pipe_buffer

commit 9d2231c5d74e13b2a0546fee6737ee4446017903 upstream.

The functions copy_page_to_iter_pipe() and push_pipe() can both
allocate a new pipe_buffer, but the "flags" member initializer is
missing.

Fixes: 241699c ("new iov_iter flavour: pipe-backed")
To: Alexander Viro <viro@zeniv.linux.org.uk>
To: linux-fsdevel@vger.kernel.org
To: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: engstk <eng.stk@sapo.pt>

lib/iov_iter.c

@@ -393,6 +393,7 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
 		return 0;
 	pipe->nrbufs++;
 	buf->ops = &page_cache_pipe_buf_ops;
+	buf->flags = 0;
 	get_page(buf->page = page);
 	buf->offset = offset;
 	buf->len = bytes;
@@ -517,6 +518,7 @@ static size_t push_pipe(struct iov_iter *i, size_t size,
 			break;
 		pipe->nrbufs++;
 		pipe->bufs[idx].ops = &default_pipe_buf_ops;
+		pipe->bufs[idx].flags = 0;
 		pipe->bufs[idx].page = page;
 		pipe->bufs[idx].offset = 0;
 		if (left <= PAGE_SIZE) {