* [PATCH v3 1/2] nvme-tcp: reject a read that transferred too few bytes
2026-08-01 8:18 [PATCH v3 0/2] nvme-tcp: two checks on the C2HData receive path Yehyeong Lee
@ 2026-08-01 8:18 ` Yehyeong Lee
2026-08-01 8:18 ` [PATCH v3 2/2] nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone Yehyeong Lee
2026-08-10 22:58 ` [PATCH v3 0/2] nvme-tcp: two checks on the C2HData receive path Keith Busch
2 siblings, 0 replies; 4+ messages in thread
From: Yehyeong Lee @ 2026-08-01 8:18 UTC (permalink / raw)
To: linux-nvme; +Cc: kbusch, axboe, hch, sagi, linux-kernel, Yehyeong Lee, stable
nvme_tcp_recv_data() completes a request once the current C2HData PDU
has been consumed. Nothing compares the total bytes received against
the length the command asked for: struct nvme_tcp_request has no
receive-side counter, queue->data_remaining is per queue, and
blk_mq_end_request() completes for blk_rq_bytes(rq) unconditionally
with no residual concept anywhere above.
A controller can therefore answer a 4096-byte read with 512 bytes and
have it reported as a complete read; user space then gets 4096 bytes of
which 3584 are whatever was already in the page. I reproduced that with
a test target.
Count the bytes received and refuse to complete a successful read whose
count does not match, at the two NVME_TCP_F_DATA_SUCCESS paths and in
nvme_tcp_process_nvme_cqe(). The success test shifts req->status right
by one, because the driver keeps the wire value there and shifts it on
completion, so the check must see what the completion path will see.
Only REQ_OP_READ is checked, because there the length comes from the
sectors the request covers; a passthrough command is built by its
submitter, which picks both command and buffer, so the kernel has
nothing to compare against.
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>
---
v2 -> v3: the success test now uses req->status >> 1, the same expression
nvme_try_complete_req() uses, so a CQE phase tag cannot evade it.
drivers/nvme/host/tcp.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index ba5c7b3e2a7c..c4fe06d424d1 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -80,6 +80,7 @@ struct nvme_tcp_request {
struct bio *curr_bio;
struct iov_iter iter;
+ u32 data_recvd;
/* send state */
size_t offset;
@@ -612,6 +613,29 @@ static void nvme_tcp_error_recovery(struct nvme_ctrl *ctrl)
queue_work(nvme_reset_wq, &to_tcp_ctrl(ctrl)->err_work);
}
+/*
+ * NVMe has no short read: a read that completes successfully must
+ * have transferred everything it asked for.
+ */
+static bool nvme_tcp_data_in_short(struct nvme_tcp_queue *queue,
+ struct request *rq)
+{
+ struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+
+ if (le16_to_cpu(req->status) >> 1)
+ return false;
+ if (req_op(rq) != REQ_OP_READ || !req->data_len)
+ return false;
+ if (likely(req->data_recvd == req->data_len))
+ return false;
+
+ dev_err(queue->ctrl->ctrl.device,
+ "queue %d tag %#x short data-in: got %u of %u\n",
+ nvme_tcp_queue_id(queue), rq->tag,
+ req->data_recvd, req->data_len);
+ return true;
+}
+
static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
struct nvme_completion *cqe)
{
@@ -631,6 +655,9 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
if (req->status == cpu_to_le16(NVME_SC_SUCCESS))
req->status = cqe->status;
+ if (unlikely(nvme_tcp_data_in_short(queue, rq)))
+ return -EPROTO;
+
if (!nvme_try_complete_req(rq, req->status, cqe->result))
nvme_complete_rq(rq);
queue->nr_cqe++;
@@ -953,6 +980,7 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
*len -= recv_len;
*offset += recv_len;
queue->data_remaining -= recv_len;
+ req->data_recvd += recv_len;
}
if (!queue->data_remaining) {
@@ -961,6 +989,8 @@ static int nvme_tcp_recv_data(struct nvme_tcp_queue *queue, struct sk_buff *skb,
queue->ddgst_remaining = NVME_TCP_DIGEST_LENGTH;
} else {
if (pdu->hdr.flags & NVME_TCP_F_DATA_SUCCESS) {
+ if (unlikely(nvme_tcp_data_in_short(queue, rq)))
+ return -EPROTO;
nvme_tcp_end_request(rq,
le16_to_cpu(req->status));
queue->nr_cqe++;
@@ -1009,6 +1039,9 @@ static int nvme_tcp_recv_ddgst(struct nvme_tcp_queue *queue,
pdu->command_id);
struct nvme_tcp_request *req = blk_mq_rq_to_pdu(rq);
+ if (unlikely(nvme_tcp_data_in_short(queue, rq)))
+ return -EPROTO;
+
nvme_tcp_end_request(rq, le16_to_cpu(req->status));
queue->nr_cqe++;
}
@@ -2736,6 +2769,7 @@ static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
req->status = cpu_to_le16(NVME_SC_SUCCESS);
req->offset = 0;
req->data_sent = 0;
+ req->data_recvd = 0;
req->pdu_len = 0;
req->pdu_sent = 0;
req->h2cdata_left = 0;
--
2.43.0
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v3 2/2] nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone
2026-08-01 8:18 [PATCH v3 0/2] nvme-tcp: two checks on the C2HData receive path Yehyeong Lee
2026-08-01 8:18 ` [PATCH v3 1/2] nvme-tcp: reject a read that transferred too few bytes Yehyeong Lee
@ 2026-08-01 8:18 ` Yehyeong Lee
2026-08-10 22:58 ` [PATCH v3 0/2] nvme-tcp: two checks on the C2HData receive path Keith Busch
2 siblings, 0 replies; 4+ messages in thread
From: Yehyeong Lee @ 2026-08-01 8:18 UTC (permalink / raw)
To: linux-nvme; +Cc: kbusch, axboe, hch, sagi, linux-kernel, Yehyeong Lee, stable
Commit 25e5cb780e62 ("nvme-tcp: fix possible crash in write_zeroes
processing") established that blk_rq_payload_bytes() must not be read
without first checking blk_rq_nr_phys_segments(), and recorded the
result in nvme_tcp_setup_cmd_pdu() as req->data_len. The receive side
was left as it was.
The two differ for REQ_OP_WRITE_ZEROES, which has no physical segments
but a non-zero blk_rq_bytes(), so setup leaves req->iter untouched
while the receive gate lets a C2HData through and nvme_tcp_recv_data()
copies into whatever the previous command on that tag left there. The
driver-private area is zeroed only when the tag set is allocated.
Reproduced with a test target that leaves a residual iterator on a tag
and then sends a C2HData for a WRITE_ZEROES command on the same tag:
BUG: KASAN: wild-memory-access in _copy_to_iter+0x642/0x1330
Write of size 512 at addr ffe728c2175dfa81 by task kworker/0:1H/103
CPU: 0 UID: 0 PID: 103 Comm: kworker/0:1H Not tainted 7.2.0-rc5-NVMETCP-gf5098b6bae76 #1 PREEMPT(lazy)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: nvme_tcp_wq nvme_tcp_io_work
Call Trace:
<TASK>
dump_stack_lvl+0x53/0x70
kasan_report+0xce/0x100
? _copy_to_iter+0x642/0x1330
kasan_check_range+0x105/0x1b0
__asan_memcpy+0x3c/0x60
_copy_to_iter+0x642/0x1330
? __pfx_sock_has_perm+0x10/0x10
? worker_thread+0x45b/0xd10
? __pfx__copy_to_iter+0x10/0x10
? _raw_spin_lock_bh+0x83/0xe0
? __pfx__raw_spin_lock_bh+0x10/0x10
__skb_datagram_iter+0xf3/0x820
? __pfx_simple_copy_to_iter+0x10/0x10
? __asan_memcpy+0x3c/0x60
? skb_copy_bits+0x58d/0x830
skb_copy_datagram_iter+0x37/0x120
nvme_tcp_recv_skb+0xa07/0x4320
? __pfx_nvme_tcp_recv_skb+0x10/0x10
__tcp_read_sock+0x1ab/0x810
? __pfx_nvme_tcp_recv_skb+0x10/0x10
? __pfx_lock_sock_nested+0x10/0x10
? __pfx___tcp_read_sock+0x10/0x10
nvme_tcp_try_recv+0x152/0x1e0
? __pfx_nvme_tcp_try_recv+0x10/0x10
? __pfx_mutex_unlock+0x10/0x10
nvme_tcp_io_work+0x1e4/0x6c0
? __schedule+0x181a/0x49f0
? __pfx_nvme_tcp_io_work+0x10/0x10
process_one_work+0x633/0x1030
Keep the blk_rq_payload_bytes() test and add req->data_len to it. The
old test is what rejects a C2HData naming a tag that is no longer in
flight, because blk_update_request() zeroes rq->__data_len on
completion; req->data_len and req->curr_bio are driver-private and
survive completion, so they cannot stand in for it. Setup initialises
the iterator only when both req->curr_bio and req->data_len are set, so
the gate now tests the same two.
Fixes: 25e5cb780e62 ("nvme-tcp: fix possible crash in write_zeroes processing")
Cc: stable@vger.kernel.org
Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
---
v2 -> v3: keep the blk_rq_payload_bytes() test and add to it; v2 replaced it
and lost the rejection of a C2HData naming a tag that is no longer in flight.
drivers/nvme/host/tcp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index c4fe06d424d1..85a87ed6df93 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -668,6 +668,7 @@ static int nvme_tcp_process_nvme_cqe(struct nvme_tcp_queue *queue,
static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
struct nvme_tcp_data_pdu *pdu)
{
+ struct nvme_tcp_request *req;
struct request *rq;
rq = nvme_find_rq(nvme_tcp_tagset(queue), pdu->command_id);
@@ -678,7 +679,8 @@ static int nvme_tcp_handle_c2h_data(struct nvme_tcp_queue *queue,
return -ENOENT;
}
- if (!blk_rq_payload_bytes(rq)) {
+ req = blk_mq_rq_to_pdu(rq);
+ if (!blk_rq_payload_bytes(rq) || !req->curr_bio || !req->data_len) {
dev_err(queue->ctrl->ctrl.device,
"queue %d tag %#x unexpected data\n",
nvme_tcp_queue_id(queue), rq->tag);
--
2.43.0
^ permalink raw reply [flat|nested] 4+ messages in thread