Linux Virtualization - Oct 2023 - [PATCH vhost v1 0/2] strictly check the acccess to the common cfg

1. fix the length of the pci_iomap_range() to the common cfg
2. add size check for the vq-reset
3. add build size check to the new common cfg items

Xuan Zhuo (2):
  virtio_pci: fix the common map size and add check for vq-reset
  virtio_pci: add build offset check for the new common cfg items

 drivers/virtio/virtio_pci_modern_dev.c | 31 ++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

--
2.32.0.3.g01195cf9f

Now, the function vp_modern_map_capability() takes the size parameter,
which corresponds to the size of virtio_pci_common_cfg. As a result,
this indicates the size of memory area to map.

However, if the _F_RING_RESET is negotiated, the extra items will be
used. Therefore, we need to use the size of virtio_pci_modre_common_cfg
to map more space.

Meanwhile, this patch checks the common cfg size when _F_RING_ERSET is
negotiated.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 27 ++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index aad7d9296e77..45d41e6c7799 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <linux/virtio_pci_modern.h>
+#include <linux/virtio_config.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/delay.h>
@@ -142,6 +143,22 @@ static inline int virtio_pci_find_capability(struct pci_dev
*dev, u8 cfg_type,
 	return 0;
 }
 
+static inline int check_common_size(struct virtio_pci_modern_device *mdev,
+				     size_t common_len)
+{
+	u64 features;
+
+	features = vp_modern_get_features(mdev);
+
+	if (features & BIT_ULL(VIRTIO_F_RING_RESET)) {
+		if (unlikely(common_len < offsetofend(struct virtio_pci_modern_common_cfg,
+						      queue_reset)))
+			return -ENOENT;
+	}
+
+	return 0;
+}
+
 /* This is part of the ABI.  Don't screw with it. */
 static inline void check_offsets(void)
 {
@@ -218,6 +235,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	int err, common, isr, notify, device;
 	u32 notify_length;
 	u32 notify_offset;
+	size_t common_len;
 	int devid;
 
 	check_offsets();
@@ -291,10 +309,14 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	err = -EINVAL;
 	mdev->common = vp_modern_map_capability(mdev, common,
 				      sizeof(struct virtio_pci_common_cfg), 4,
-				      0, sizeof(struct virtio_pci_common_cfg),
-				      NULL, NULL);
+				      0, sizeof(struct virtio_pci_modern_common_cfg),
+				      &common_len, NULL);
 	if (!mdev->common)
 		goto err_map_common;
+
+	if (check_common_size(mdev, common_len))
+		goto err_common_size;
+
 	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
 					     0, 1,
 					     NULL, NULL);
@@ -353,6 +375,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 err_map_notify:
 	pci_iounmap(pci_dev, mdev->isr);
 err_map_isr:
+err_common_size:
 	pci_iounmap(pci_dev, mdev->common);
 err_map_common:
 	pci_release_selected_regions(pci_dev, mdev->modern_bars);
-- 
2.32.0.3.g01195cf9f

Add checks to the check_offsets(void) for queue_notify_data and
queue_reset.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index 45d41e6c7799..3a49bc963a71 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -220,6 +220,10 @@ static inline void check_offsets(void)
 		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI ! 		     offsetof(struct
virtio_pci_common_cfg, queue_used_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NDATA !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_notify_data));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_RESET !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_reset));
 }
 
 /*
-- 
2.32.0.3.g01195cf9f