[PATCH v4] mpt3sas: Limit NVMe request size to 2 MiB

[Ranjan Kumar <ranjan.kumar@broadcom.com>]

The HBA firmware reports NVMe MDTS values based on the underlying drive
capability. However, because the driver allocates a fixed 4K buffer for
the PRP list, accommodating at most 512 entries, the driver supports a
maximum I/O transfer size of 2 MiB.

Limit max_hw_sectors to the smaller of the reported MDTS and the
2 MiB driver limit to prevent issuing oversized I/O that may lead
to a kernel oops.

Cc: stable@vger.kernel.org
Fixes: 9b8b84879d4a ("block: Increase BLK_DEF_MAX_SECTORS_CAP")
Reported-by: Mira Limbeck <m.limbeck@proxmox.com>
Closes: https://lore.kernel.org/r/291f78bf-4b4a-40dd-867d-053b36c564b3@proxmox.com
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9b8b84879d4a
Suggested-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
---
 drivers/scsi/mpt3sas/mpt3sas_scsih.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index 6ff788557294..12caffeed3a0 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -2738,8 +2738,20 @@ scsih_sdev_configure(struct scsi_device *sdev, struct queue_limits *lim)
 				pcie_device->enclosure_level,
 				pcie_device->connector_name);
 
+		/*
+		 * The HBA firmware passes the NVMe drive's MDTS
+		 * (Maximum Data Transfer Size) up to the driver. However,
+		 * the driver hardcodes a 4K buffer size for the PRP list,
+		 * accommodating at most 512 entries. This strictly limits
+		 * the maximum supported NVMe I/O transfer to 2 MiB.
+		 *
+		 * Cap max_hw_sectors to the smaller of the drive's reported
+		 * MDTS or the 2 MiB driver limit to prevent kernel oopses.
+		 */
+		lim->max_hw_sectors = SZ_2M >> SECTOR_SHIFT;
 		if (pcie_device->nvme_mdts)
-			lim->max_hw_sectors = pcie_device->nvme_mdts / 512;
+			lim->max_hw_sectors = min(lim->max_hw_sectors,
+					pcie_device->nvme_mdts >> SECTOR_SHIFT);
 
 		pcie_device_put(pcie_device);
 		spin_unlock_irqrestore(&ioc->pcie_device_lock, flags);
-- 
2.47.3