Patch "nvme-pci: use sgls for all user requests if possible" has been added to the 6.12-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    nvme-pci: use sgls for all user requests if possible

to the 6.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nvme-pci-use-sgls-for-all-user-requests-if-possible.patch
and it can be found in the queue-6.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit e958b0165c3bdf8fea8906e68c8efd8eb11f4b7c
Author: Keith Busch <kbusch@xxxxxxxxxx>
Date:   Fri Nov 8 15:41:08 2024 -0800

    nvme-pci: use sgls for all user requests if possible
    
    [ Upstream commit 6fad84a4d624c300d03ebba457cc641765050c43 ]
    
    If the device supports SGLs, use these for all user requests. This
    format encodes the expected transfer length so it can catch short buffer
    errors in a user command, whether it occurred accidently or maliciously.
    
    For controllers that support SGL data mode, this is a viable mitigation
    to CVE-2023-6238. For controllers that don't support SGLs, log a warning
    in the passthrough path since not having the capability can corrupt
    data if the interface is not used correctly.
    
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
    Stable-dep-of: 00817f0f1c45 ("nvme-ioctl: fix leaked requests on mapping error")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 61af1583356c2..d4b80938de09c 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -120,12 +120,20 @@ static int nvme_map_user_request(struct request *req, u64 ubuffer,
 	struct nvme_ns *ns = q->queuedata;
 	struct block_device *bdev = ns ? ns->disk->part0 : NULL;
 	bool supports_metadata = bdev && blk_get_integrity(bdev->bd_disk);
+	struct nvme_ctrl *ctrl = nvme_req(req)->ctrl;
 	bool has_metadata = meta_buffer && meta_len;
 	struct bio *bio = NULL;
 	int ret;
 
-	if (has_metadata && !supports_metadata)
-		return -EINVAL;
+	if (!nvme_ctrl_sgl_supported(ctrl))
+		dev_warn_once(ctrl->device, "using unchecked data buffer\n");
+	if (has_metadata) {
+		if (!supports_metadata)
+			return -EINVAL;
+		if (!nvme_ctrl_meta_sgl_supported(ctrl))
+			dev_warn_once(ctrl->device,
+				      "using unchecked metadata buffer\n");
+	}
 
 	if (ioucmd && (ioucmd->flags & IORING_URING_CMD_FIXED)) {
 		struct iov_iter iter;
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 58bdd0da6b658..e1329d4974fd6 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -514,7 +514,8 @@ static inline bool nvme_pci_metadata_use_sgls(struct nvme_dev *dev,
 {
 	if (!nvme_ctrl_meta_sgl_supported(&dev->ctrl))
 		return false;
-	return req->nr_integrity_segments > 1;
+	return req->nr_integrity_segments > 1 ||
+		nvme_req(req)->flags & NVME_REQ_USERCMD;
 }
 
 static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
@@ -532,7 +533,7 @@ static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req,
 	if (nvme_pci_metadata_use_sgls(dev, req))
 		return true;
 	if (!sgl_threshold || avg_seg_size < sgl_threshold)
-		return false;
+		return nvme_req(req)->flags & NVME_REQ_USERCMD;
 	return true;
 }