[PATCH] nvme-tcp: fix possible crash in write_zeroes processing

[PATCH] nvme-tcp: fix possible crash in write_zeroes processing

[Sagi Grimberg]

We cannot look at blk_rq_payload_bytes without first checking
that the request has a mappable physical segments first (e.g.
blk_rq_nr_phys_segments(rq) != 0) and only then to take the
request payload bytes. This caused us to send a wrong sgl to
the target or even dereference a non-existing buffer in case
we actually got to the data send sequence (if it was in-capsule).

Reported-by: Tony Asleson <tasleson@redhat.com>
Suggested-by: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
---
 drivers/nvme/host/tcp.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 11e10fe1760f..b545a9e96327 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -177,16 +177,14 @@ static inline bool nvme_tcp_async_req(struct nvme_tcp_request *req)
 static inline bool nvme_tcp_has_inline_data(struct nvme_tcp_request *req)
 {
 	struct request *rq;
-	unsigned int bytes;
 
 	if (unlikely(nvme_tcp_async_req(req)))
 		return false; /* async events don't have a request */
 
 	rq = blk_mq_rq_from_pdu(req);
-	bytes = blk_rq_payload_bytes(rq);
 
-	return rq_data_dir(rq) == WRITE && bytes &&
-		bytes <= nvme_tcp_inline_data_size(req->queue);
+	return rq_data_dir(rq) == WRITE && req->data_len &&
+		req->data_len <= nvme_tcp_inline_data_size(req->queue);
 }
 
 static inline struct page *nvme_tcp_req_cur_page(struct nvme_tcp_request *req)
@@ -2182,7 +2180,9 @@ static blk_status_t nvme_tcp_map_data(struct nvme_tcp_queue *queue,
 
 	c->common.flags |= NVME_CMD_SGL_METABUF;
 
-	if (rq_data_dir(rq) == WRITE && req->data_len &&
+	if (!blk_rq_nr_phys_segments(rq))
+		nvme_tcp_set_sg_null(c);
+	else if (rq_data_dir(rq) == WRITE &&
 	    req->data_len <= nvme_tcp_inline_data_size(queue))
 		nvme_tcp_set_sg_inline(queue, c, req->data_len);
 	else
@@ -2209,7 +2209,8 @@ static blk_status_t nvme_tcp_setup_cmd_pdu(struct nvme_ns *ns,
 	req->data_sent = 0;
 	req->pdu_len = 0;
 	req->pdu_sent = 0;
-	req->data_len = blk_rq_payload_bytes(rq);
+	req->data_len = blk_rq_nr_phys_segments(rq) ?
+				blk_rq_payload_bytes(rq) : 0;
 	req->curr_bio = rq->bio;
 
 	if (rq_data_dir(rq) == WRITE &&
-- 
2.20.1


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Re: [PATCH] nvme-tcp: fix possible crash in write_zeroes processing

[Keith Busch]

On Mon, Mar 23, 2020 at 03:06:30PM -0700, Sagi Grimberg wrote:
> We cannot look at blk_rq_payload_bytes without first checking
> that the request has a mappable physical segments first (e.g.
> blk_rq_nr_phys_segments(rq) != 0) and only then to take the
> request payload bytes. This caused us to send a wrong sgl to
> the target or even dereference a non-existing buffer in case
> we actually got to the data send sequence (if it was in-capsule).
> 
> Reported-by: Tony Asleson <tasleson@redhat.com>
> Suggested-by: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

Applied for 5.6, thanks.

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