Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Dylan Yudaken <dylany@fb.com>
To:     Jens Axboe <axboe@kernel.dk>,
        Pavel Begunkov <asml.silence@gmail.com>,
        <io-uring@vger.kernel.org>
CC:     <Kernel-team@fb.com>, <linux-kernel@vger.kernel.org>,
        Dylan Yudaken <dylany@fb.com>
Subject: [PATCH for-next 1/8] io_uring: allow 0 length for buffer select
Date:   Tue, 28 Jun 2022 08:02:21 -0700
Message-ID: <20220628150228.1379645-2-dylany@fb.com>
In-Reply-To: <20220628150228.1379645-1-dylany@fb.com>
References: <20220628150228.1379645-1-dylany@fb.com>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain
Precedence: bulk

If user gives 0 for length, we can set it from the available buffer size.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 io_uring/kbuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 8e4f1e8aaf4a..4ed5102461bf 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -115,7 +115,7 @@ static void __user *io_provided_buffer_select(struct =
io_kiocb *req, size_t *len,
=20
 		kbuf =3D list_first_entry(&bl->buf_list, struct io_buffer, list);
 		list_del(&kbuf->list);
-		if (*len > kbuf->len)
+		if (*len =3D=3D 0 || *len > kbuf->len)
 			*len =3D kbuf->len;
 		req->flags |=3D REQ_F_BUFFER_SELECTED;
 		req->kbuf =3D kbuf;
@@ -145,7 +145,7 @@ static void __user *io_ring_buffer_select(struct io_k=
iocb *req, size_t *len,
 		buf =3D page_address(bl->buf_pages[index]);
 		buf +=3D off;
 	}
-	if (*len > buf->len)
+	if (*len =3D=3D 0 || *len > buf->len)
 		*len =3D buf->len;
 	req->flags |=3D REQ_F_BUFFER_RING;
 	req->buf_list =3D bl;
--=20
2.30.2