FAILED: patch "[PATCH] nvme-tcp: fix host memory disclosure on R2T for a read" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 6efbc52237facda35d2d874fe1765bb4839275d8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090304-lazily-cauterize-57c7@gregkh' --subject-prefix 'PATCH 5.10.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 6efbc52237facda35d2d874fe1765bb4839275d8 Mon Sep 17 00:00:00 2001
From: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
Date: Wed, 29 Jul 2026 14:46:02 +0900
Subject: [PATCH] nvme-tcp: fix host memory disclosure on R2T for a read
 command

nvme_tcp_handle_r2t() does not check the direction of the request the
R2T refers to. A malicious controller can send an R2T for a READ and
the host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the
H2CData header and nvme_tcp_try_send_data() sends the request's data
buffer. That buffer is the READ destination, so its contents go to the
controller.

The command then completes normally and nothing is logged.

Against a test controller that answers every READ with an R2T, a 4096
byte buffered read returned all 4096 bytes, split over two R2Ts. The
pages contained stale kernel data, including an array of struct page
pointers.

Reject an R2T for a request that is not a write.

Fixes: 3f2304f8c6d6 ("nvme-tcp: add NVMe over TCP host driver")
Cc: stable@vger.kernel.org
Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 46c2acc6abe0..62c5e38f5207 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -779,6 +779,13 @@ static int nvme_tcp_handle_r2t(struct nvme_tcp_queue *queue,
 	}
 	req = blk_mq_rq_to_pdu(rq);
 
+	if (unlikely(rq_data_dir(rq) != WRITE)) {
+		dev_err(queue->ctrl->ctrl.device,
+			"req %d unexpected r2t for a non-write command\n",
+			rq->tag);
+		return -EPROTO;
+	}
+
 	if (unlikely(!r2t_length)) {
 		dev_err(queue->ctrl->ctrl.device,
 			"req %d r2t len is %u, probably a bug...\n",