[PATCH] nvme-core: check for too small lba shift

[Keith Busch]

From: Keith Busch <kbusch at kernel.org>

The block layer doesn't support logical block sizes smaller than 512
bytes. The nvme spec doesn't support that small either, but the driver
isn't checking to make sure the device responded with usable data.
Failing to catch this will result in a kernel bug, either from a
division by zero when stacking, or a zero length bio.

Signed-off-by: Keith Busch <kbusch at kernel.org>
---
 drivers/nvme/host/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index a55c2a774b9c4..1be1ce5228965 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1901,9 +1901,10 @@ static void nvme_update_disk_info(struct gendisk *disk,
 
 	/*
 	 * The block layer can't support LBA sizes larger than the page size
-	 * yet, so catch this early and don't allow block I/O.
+	 * or smaller than a sector size yet, so catch this early and don't
+	 * allow block I/O.
 	 */
-	if (ns->lba_shift > PAGE_SHIFT) {
+	if (ns->lba_shift > PAGE_SHIFT || ns->lba_shift < SECTOR_SHIFT) {
 		capacity = 0;
 		bs = (1 << 9);
 	}
-- 
2.34.1