From 6efbc52237facda35d2d874fe1765bb4839275d8 Mon Sep 17 00:00:00 2001 From: Yehyeong Lee 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 Signed-off-by: Keith Busch --- drivers/nvme/host/tcp.c | 7 +++++++ 1 file changed, 7 insertions(+) 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",