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From: Gabriel Krisman Bertazi <[email protected]>
To: [email protected]
Cc: [email protected], Gabriel Krisman Bertazi <[email protected]>
Subject: [PATCH] io_uring: Require zeroed sqe->len on provided-buffers send
Date: Mon, 29 Apr 2024 14:15:56 -0400	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

When sending from a provided buffer, we set sr->len to be the smallest
between the actual buffer size and sqe->len.  But, now that we
disconnect the buffer from the submission request, we can get in a
situation where the buffers and requests mismatch, and only part of a
buffer gets sent.  Assume:

* buf[1]->len = 128; buf[2]->len = 256
* sqe[1]->len = 128; sqe[2]->len = 256

If sqe1 runs first, it picks buff[1] and it's all good. But, if sqe[2]
runs first, sqe[1] picks buff[2], and the last half of buff[2] is
never sent.

While arguably the use-case of different-length sends is questionable,
it has already raised confusion with potential users of this
feature. Let's make the interface less tricky by forcing the length to
only come from the buffer ring entry itself.

Fixes: ac5f71a3d9d7 ("io_uring/net: add provided buffer support for IORING_OP_SEND")
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
---
 io_uring/net.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/io_uring/net.c b/io_uring/net.c
index 51c41d771c50..ffe37dd77a74 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -423,6 +423,8 @@ int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		sr->buf_group = req->buf_index;
 		req->buf_list = NULL;
 	}
+	if (req->flags & REQ_F_BUFFER_SELECT && sr->len)
+		return -EINVAL;
 
 #ifdef CONFIG_COMPAT
 	if (req->ctx->compat)
-- 
2.44.0


  reply	other threads:[~2024-04-29 18:16 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-20 13:29 [PATCHSET v2 0/5] Send and receive bundles Jens Axboe
2024-04-20 13:29 ` [PATCH 1/5] io_uring/net: add generic multishot retry helper Jens Axboe
2024-04-20 13:29 ` [PATCH 2/5] io_uring/net: add provided buffer support for IORING_OP_SEND Jens Axboe
2024-04-25 11:56   ` Gabriel Krisman Bertazi
2024-04-25 12:19     ` Gabriel Krisman Bertazi
2024-04-25 15:11     ` Jens Axboe
2024-04-29 18:15       ` Gabriel Krisman Bertazi [this message]
2024-04-30 13:02         ` [PATCH] io_uring: Require zeroed sqe->len on provided-buffers send Jens Axboe
2024-05-01 20:47           ` Gabriel Krisman Bertazi
2024-05-01 20:55             ` Jens Axboe
2024-04-20 13:29 ` [PATCH 3/5] io_uring/kbuf: add helpers for getting/peeking multiple buffers Jens Axboe
2024-04-20 13:29 ` [PATCH 4/5] io_uring/net: support bundles for send Jens Axboe
2024-04-20 13:29 ` [PATCH 5/5] io_uring/net: support bundles for recv Jens Axboe

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