From: =?UTF-8?q?Jan=20H=2E=20Sch=C3=B6nherr?= <jschoenh@amazon.de>
Date: Sun, 27 Aug 2017 15:56:37 +0200
Subject: nvme: fix uninitialized prp2 value on small transfers
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Patch-mainline: v4.14-rc1
Git-commit: 5228b3280b9bb8fa6aef59f891cca64a028e9b36
References: FATE#323952, FATE#322506

The value of iod->first_dma ends up as prp2 in NVMe commands. In case
there is not enough data to cross a page boundary, iod->first_dma is
never initialized and contains random data.

Comply with the NVMe specification and fill in 0 in that case.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Thumshirn <jthumshirn@suse.de>
---
 drivers/nvme/host/pci.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -556,8 +556,10 @@ static blk_status_t nvme_setup_prps(stru
 	int nprps, i;
 
 	length -= (page_size - offset);
-	if (length <= 0)
+	if (length <= 0) {
+		iod->first_dma = 0;
 		return BLK_STS_OK;
+	}
 
 	dma_len -= (page_size - offset);
 	if (dma_len) {