FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.12-stable tree

FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.12-stable tree

[gregkh]

The patch below does not apply to the 6.12-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-6.12.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 '2025081548-whoops-aneurism-c7b1@gregkh' --subject-prefix 'PATCH 6.12.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 6.12-stable tree

[Jens Axboe]

[-- Attachment #1: Type: text/plain, Size: 822 bytes --]

On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.12-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-6.12.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 '2025081548-whoops-aneurism-c7b1@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Trivial reject, here's one for 6.12-stable.

-- 
Jens Axboe

[-- Attachment #2: 0001-io_uring-net-commit-partial-buffers-on-retry.patch --]
[-- Type: text/x-patch, Size: 3934 bytes --]

From a6dfda7da5c65b282c1663326be16e57aec3d1bd 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>
---
 io_uring/net.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 356f95c33aa2..b7c93765fcff 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -498,6 +498,15 @@ 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 -EAGAIN;
+}
+
 static inline bool io_send_finish(struct io_kiocb *req, int *ret,
 				  struct io_async_msghdr *kmsg,
 				  unsigned issue_flags)
@@ -566,8 +575,7 @@ 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;
@@ -664,8 +672,7 @@ 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;
@@ -1068,8 +1075,7 @@ 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 -EAGAIN;
+			return io_net_kbuf_recyle(req, kmsg, ret);
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
@@ -1211,8 +1217,7 @@ 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;
@@ -1441,8 +1446,7 @@ 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;
@@ -1502,8 +1506,7 @@ 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;
-- 
2.50.1

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.12-stable tree

[Jens Axboe]

On Fri, Aug 15, 2025 at 9:35?AM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
> >
> > The patch below does not apply to the 6.12-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-6.12.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 '2025081548-whoops-aneurism-c7b1@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
>
> Trivial reject, here's one for 6.12-stable.

This didn't get included in the release yesterday?

-- 
Jens Axboe

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.12-stable tree

[Greg KH]

On Thu, Aug 21, 2025 at 03:46:33PM -0600, Jens Axboe wrote:
> On Fri, Aug 15, 2025 at 9:35?AM Jens Axboe <axboe@kernel.dk> wrote:
> >
> > On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
> > >
> > > The patch below does not apply to the 6.12-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-6.12.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 '2025081548-whoops-aneurism-c7b1@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
> >
> > Trivial reject, here's one for 6.12-stable.
> 
> This didn't get included in the release yesterday?

Ick, this got dropped somehow, sorry about that.  I'll go queue it up
now, thanks for noticing.

greg k-h

Re: FAILED: patch "[PATCH] io_uring/net: commit partial buffers on retry" failed to apply to 6.12-stable tree

[Jens Axboe]

On 8/22/25 12:27 AM, Greg KH wrote:
> On Thu, Aug 21, 2025 at 03:46:33PM -0600, Jens Axboe wrote:
>> On Fri, Aug 15, 2025 at 9:35?AM Jens Axboe <axboe@kernel.dk> wrote:
>>>
>>> On 8/15/25 9:26 AM, gregkh@linuxfoundation.org wrote:
>>>>
>>>> The patch below does not apply to the 6.12-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-6.12.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 '2025081548-whoops-aneurism-c7b1@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
>>>
>>> Trivial reject, here's one for 6.12-stable.
>>
>> This didn't get included in the release yesterday?
> 
> Ick, this got dropped somehow, sorry about that.  I'll go queue it up
> now, thanks for noticing.

I always check when I drop the private patch(es) in the branch and pull
the update, and when I did that yesterday it was a wtf moment.

-- 
Jens Axboe