diff options
| author | Venkatesh Srinivas <venkateshs@google.com> | 2019-01-23 11:27:51 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-01-31 16:22:51 +0100 |
| commit | 865a11f987ab5f03089b2728420b61a2a1f7051a (patch) | |
| tree | 297392fb063a48e7b8faa6db2759453703dc6030 /drivers/uio/uio_pci_generic.c | |
| parent | e5bae74338b37fb88d33d7c18acb694670c24b09 (diff) | |
uio/uio_pci_generic: Disable bus-mastering on release
Userspace code using uio_pci_generic may enable bus-mastering by
directly manipulating a PCI device's command register. If a userspace
program enables bus-mastering but exits/crashes uncleanly, bus-
mastering will still be enabled and stale DMA addresses may be
programmed and live in the device.
Disable bus-mastering unconditionally on last close of a UIO PCI fd
to avoid this. If the device did not have bus-mastering enabled,
pci_clear_master() is a no-op.
Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/uio/uio_pci_generic.c')
| -rw-r--r-- | drivers/uio/uio_pci_generic.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c index 8773e373ffe5..dde5cbb27178 100644 --- a/drivers/uio/uio_pci_generic.c +++ b/drivers/uio/uio_pci_generic.c @@ -39,6 +39,22 @@ to_uio_pci_generic_dev(struct uio_info *info) return container_of(info, struct uio_pci_generic_dev, info); } +static int release(struct uio_info *info, struct inode *inode) +{ + struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info); + + /* + * This driver is insecure when used with devices doing DMA, but some + * people (mis)use it with such devices. + * Let's at least make sure DMA isn't left enabled after the userspace + * driver closes the fd. + * Note that there's a non-zero chance doing this will wedge the device + * at least until reset. + */ + pci_clear_master(gdev->pdev); + return 0; +} + /* Interrupt handler. Read/modify/write the command register to disable * the interrupt. */ static irqreturn_t irqhandler(int irq, struct uio_info *info) @@ -78,6 +94,7 @@ static int probe(struct pci_dev *pdev, gdev->info.name = "uio_pci_generic"; gdev->info.version = DRIVER_VERSION; + gdev->info.release = release; gdev->pdev = pdev; if (pdev->irq) { gdev->info.irq = pdev->irq; |