[PATCH 93/98] nvmet-fc: only send read data for successful commands

[Jens Axboe <axboe@kernel.dk>]

From: Andrea Parri <parri.andrea@gmail.com>

__nvmet_fc_fcp_nvme_cmd_done() pushes the whole data buffer of a read
to the host even when the command failed. The buffer comes from
sgl_alloc() without __GFP_ZERO, and a command rejected by
nvmet_check_transfer_len() never touches it, so the host receives stale
target memory, as much as it asked for.

The tcp and rdma targets only send data when cqe->status is zero. Do
the same for fc. The ERSP then reports fod->offset, which is 0, as the
transferred length, matching what the host checks.

Fixes: c53432030d86 ("nvme-fabrics: Add target support for FC transport")
Cc: stable@vger.kernel.org
Cc: Justin Tee <justin.tee@broadcom.com>
Cc: Naresh Gottumukkala <nareshgottumukkala83@gmail.com>
Cc: Paul Ely <paul.ely@broadcom.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Chris Mason <mason@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 drivers/nvme/target/fc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index eecdffefa24f..b95893adae36 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -2487,11 +2487,11 @@ __nvmet_fc_fcp_nvme_cmd_done(struct nvmet_fc_tgtport *tgtport,
 	} else {
 
 		/*
-		 * try to push the data even if the SQE status is non-zero.
-		 * There may be a status where data still was intended to
-		 * be moved
+		 * A failed command may not have filled its read buffer, so
+		 * only push data for success, as the tcp and rdma targets do.
 		 */
-		if ((fod->io_dir == NVMET_FCP_READ) && (fod->data_sg_cnt)) {
+		if (fod->io_dir == NVMET_FCP_READ && fod->data_sg_cnt &&
+		    !cqe->status) {
 			/* push the data over before sending rsp */
 			nvmet_fc_transfer_fcp_data(tgtport, fod,
 						NVMET_FCOP_READDATA);
-- 
2.56.0