FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 41b70df5b38bc80967d2e0ed55cc3c3896bba781
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025081549-shorter-borrower-941d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 41b70df5b38bc80967d2e0ed55cc3c3896bba781 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 12 Aug 2025 08:30:11 -0600
Subject: [PATCH] io_uring/net: commit partial buffers on retry

Ring provided buffers are potentially only valid within the single
execution context in which they were acquired. io_uring deals with this
and invalidates them on retry. But on the networking side, if
MSG_WAITALL is set, or if the socket is of the streaming type and too
little was processed, then it will hang on to the buffer rather than
recycle or commit it. This is problematic for two reasons:

1) If someone unregisters the provided buffer ring before a later retry,
   then the req->buf_list will no longer be valid.

2) If multiple sockers are using the same buffer group, then multiple
   receives can consume the same memory. This can cause data corruption
   in the application, as either receive could land in the same
   userspace buffer.

Fix this by disallowing partial retries from pinning a provided buffer
across multiple executions, if ring provided buffers are used.

Cc: stable@vger.kernel.org
Reported-by: pt x <superman.xpt@gmail.com>
Fixes: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/net.c b/io_uring/net.c
index dd96e355982f..d69f2afa4f7a 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -494,6 +494,15 @@ static int io_bundle_nbufs(struct io_async_msghdr *kmsg, int ret)
 	return nbufs;
 }
 
+static int io_net_kbuf_recyle(struct io_kiocb *req,
+			      struct io_async_msghdr *kmsg, int len)
+{
+	req->flags |= REQ_F_BL_NO_RECYCLE;
+	if (req->flags & REQ_F_BUFFERS_COMMIT)
+		io_kbuf_commit(req, req->buf_list, len, io_bundle_nbufs(kmsg, len));
+	return IOU_RETRY;
+}
+
 static inline bool io_send_finish(struct io_kiocb *req, int *ret,
 				  struct io_async_msghdr *kmsg,
 				  unsigned issue_flags)
@@ -562,8 +571,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 			kmsg->msg.msg_controllen = 0;
 			kmsg->msg.msg_control = NULL;
 			sr->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -674,8 +682,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1071,8 +1078,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 		}
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return IOU_RETRY;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1218,8 +1224,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1500,8 +1505,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 			zc->len -= ret;
 			zc->buf += ret;
 			zc->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1571,8 +1575,7 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
-			req->flags |= REQ_F_BL_NO_RECYCLE;
-			return -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.6-stable tree

[Jens Axboe]

[-- Attachment #1: Type: text/plain, Size: 803 bytes --]

On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.6-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
> git checkout FETCH_HEAD
> git cherry-pick -x 41b70df5b38bc80967d2e0ed55cc3c3896bba781
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025081549-shorter-borrower-941d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Here's one for 6.6-stable.

-- 
Jens Axboe

[-- Attachment #2: 0001-io_uring-net-commit-partial-buffers-on-retry.patch --]
[-- Type: text/x-patch, Size: 3740 bytes --]

From c16cb4e2a4b1a487ca7feae5931dfb22ac495b76 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 12 Aug 2025 08:30:11 -0600
Subject: [PATCH] io_uring/net: commit partial buffers on retry

Commit a6dfda7da5c65b282c1663326be16e57aec3d1bd upstream.

Ring provided buffers are potentially only valid within the single
execution context in which they were acquired. io_uring deals with this
and invalidates them on retry. But on the networking side, if
MSG_WAITALL is set, or if the socket is of the streaming type and too
little was processed, then it will hang on to the buffer rather than
recycle or commit it. This is problematic for two reasons:

1) If someone unregisters the provided buffer ring before a later retry,
   then the req->buf_list will no longer be valid.

2) If multiple sockers are using the same buffer group, then multiple
   receives can consume the same memory. This can cause data corruption
   in the application, as either receive could land in the same
   userspace buffer.

Fix this by disallowing partial retries from pinning a provided buffer
across multiple executions, if ring provided buffers are used.

Cc: stable@vger.kernel.org
Reported-by: pt x <superman.xpt@gmail.com>
Fixes: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/net.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index e455f051e62e..e7f8a79e049c 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -351,6 +351,13 @@ static int io_setup_async_addr(struct io_kiocb *req,
 	return -EAGAIN;
 }
 
+static void io_net_kbuf_recyle(struct io_kiocb *req)
+{
+	req->flags |= REQ_F_PARTIAL_IO;
+	if (req->flags & REQ_F_BUFFER_RING)
+		io_kbuf_recycle_ring(req);
+}
+
 int io_sendmsg_prep_async(struct io_kiocb *req)
 {
 	int ret;
@@ -442,7 +449,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 			kmsg->msg.msg_controllen = 0;
 			kmsg->msg.msg_control = NULL;
 			sr->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return io_setup_async_msg(req, kmsg, issue_flags);
 		}
 		if (ret == -ERESTARTSYS)
@@ -521,7 +528,7 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return io_setup_async_addr(req, &__address, issue_flags);
 		}
 		if (ret == -ERESTARTSYS)
@@ -891,7 +898,7 @@ int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
 		}
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return io_setup_async_msg(req, kmsg, issue_flags);
 		}
 		if (ret == -ERESTARTSYS)
@@ -991,7 +998,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 			sr->len -= ret;
 			sr->buf += ret;
 			sr->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
@@ -1235,7 +1242,7 @@ int io_send_zc(struct io_kiocb *req, unsigned int issue_flags)
 			zc->len -= ret;
 			zc->buf += ret;
 			zc->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return io_setup_async_addr(req, &__address, issue_flags);
 		}
 		if (ret == -ERESTARTSYS)
@@ -1306,7 +1313,7 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->done_io += ret;
-			req->flags |= REQ_F_PARTIAL_IO;
+			io_net_kbuf_recyle(req);
 			return io_setup_async_msg(req, kmsg, issue_flags);
 		}
 		if (ret == -ERESTARTSYS)
-- 
2.50.1

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.6-stable tree

[Greg KH]

On Fri, Aug 15, 2025 at 09:46:53AM -0600, Jens Axboe wrote:
> On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 6.6-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > To reproduce the conflict and resubmit, you may use the following commands:
> > 
> > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
> > git checkout FETCH_HEAD
> > git cherry-pick -x 41b70df5b38bc80967d2e0ed55cc3c3896bba781
> > # <resolve conflicts, build, test, etc.>
> > git commit -s
> > git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025081549-shorter-borrower-941d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
> 
> Here's one for 6.6-stable.
> 
> -- 
> Jens Axboe

> From c16cb4e2a4b1a487ca7feae5931dfb22ac495b76 Mon Sep 17 00:00:00 2001
> From: Jens Axboe <axboe@kernel.dk>
> Date: Tue, 12 Aug 2025 08:30:11 -0600
> Subject: [PATCH] io_uring/net: commit partial buffers on retry
> 
> Commit a6dfda7da5c65b282c1663326be16e57aec3d1bd upstream.

Nit, wrong git id :(

I'll go fix it, thanks.

greg k-h

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.6-stable tree

[Jens Axboe]

On 8/15/25 9:57 AM, Greg KH wrote:
> On Fri, Aug 15, 2025 at 09:46:53AM -0600, Jens Axboe wrote:
>> On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
>>>
>>> The patch below does not apply to the 6.6-stable tree.
>>> If someone wants it applied there, or to any other stable or longterm
>>> tree, then please email the backport, including the original git commit
>>> id to <stable@vger.kernel.org>.
>>>
>>> To reproduce the conflict and resubmit, you may use the following commands:
>>>
>>> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
>>> git checkout FETCH_HEAD
>>> git cherry-pick -x 41b70df5b38bc80967d2e0ed55cc3c3896bba781
>>> # <resolve conflicts, build, test, etc.>
>>> git commit -s
>>> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025081549-shorter-borrower-941d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
>>
>> Here's one for 6.6-stable.
>>
>> -- 
>> Jens Axboe
> 
>> From c16cb4e2a4b1a487ca7feae5931dfb22ac495b76 Mon Sep 17 00:00:00 2001
>> From: Jens Axboe <axboe@kernel.dk>
>> Date: Tue, 12 Aug 2025 08:30:11 -0600
>> Subject: [PATCH] io_uring/net: commit partial buffers on retry
>>
>> Commit a6dfda7da5c65b282c1663326be16e57aec3d1bd upstream.
> 
> Nit, wrong git id :(
> 
> I'll go fix it, thanks.

Oops sorry about that, guess I took it from the other my other backport
rather than upstream.

-- 
Jens Axboe