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virtio: pci: check bar values read from virtio config space

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virtio pci config structures may in future have non-standard bar
values in the bar field. We should anticipate this by skipping any
structures containing such a reserved value.

The bar value should never change: check for harmful modified values
we re-read it from the config space in vp_modern_map_capability().

Also clean up an existing check to consistently use PCI_STD_NUM_BARS.

Signed-off-by: Keir Fraser <keirf@google.com>
Link: https://lore.kernel.org/r/20220323140727.3499235-1-keirf@google.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Keir Fraser
2022-03-23 14:07:27 +00:00
committed by Michael S. Tsirkin
parent eb4cecb453
commit 3f63a1d7f6
2 changed files with 17 additions and 4 deletions
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9
drivers/virtio/virtio_pci_modern_dev.c
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@@ -35,6 +35,13 @@ vp_modern_map_capability(struct virtio_pci_modern_device *mdev, int off,
pci_read_config_dword(dev, off + offsetof(struct virtio_pci_cap, length),
&length);
/* Check if the BAR may have changed since we requested the region. */
if (bar >= PCI_STD_NUM_BARS || !(mdev->modern_bars & (1 << bar))) {
dev_err(&dev->dev,
"virtio_pci: bar unexpectedly changed to %u\n", bar);
return NULL;
}
if (length <= start) {
dev_err(&dev->dev,
"virtio_pci: bad capability len %u (>%u expected)\n",
@@ -120,7 +127,7 @@ static inline int virtio_pci_find_capability(struct pci_dev *dev, u8 cfg_type,
&bar);
/* Ignore structures with reserved BAR values */
if (bar > 0x5)
if (bar >= PCI_STD_NUM_BARS)
continue;
if (type == cfg_type) {