[PATCH vhost v1 1/2] virtio_pci: fix the common map size and add check for vq-reset

[Xuan Zhuo]

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 <xuanz...@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

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