diff options
| author | Robin Murphy <robin.murphy@arm.com> | 2025-04-25 14:39:29 +0100 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2025-07-15 15:23:59 -0500 |
| commit | 78447d4545b2ea76ee04f4e46d473639483158b2 (patch) | |
| tree | 5ecab4366b772e1f2afd68b4712aa0ceac5a69ab /drivers/pci | |
| parent | 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 (diff) | |
PCI: Fix driver_managed_dma check
Since it's not currently safe to take device_lock() in the IOMMU probe
path, that can race against really_probe() setting dev->driver before
attempting to bind. The race itself isn't so bad, since we're only
concerned with dereferencing dev->driver itself anyway, but sadly my
attempt to implement the check with minimal churn leads to a kind of
Time-of-Check to Time-of-Use (TOCTOU) issue, where dev->driver becomes
valid after to_pci_driver(NULL) is already computed, and thus the check
fails to work as intended.
Will and I both hit this with the platform bus, but the pattern here is
the same, so fix it for correctness too.
Fixes: bcb81ac6ae3c ("iommu: Get DT/ACPI parsing into the proper probe path")
Reported-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Will McVicker <willmcvicker@google.com>
Link: https://patch.msgid.link/20250425133929.646493-4-robin.murphy@arm.com
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/pci-driver.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 67db34fd10ee..01e6aea1b0c7 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -1628,7 +1628,7 @@ static int pci_bus_num_vf(struct device *dev) */ static int pci_dma_configure(struct device *dev) { - struct pci_driver *driver = to_pci_driver(dev->driver); + const struct device_driver *drv = READ_ONCE(dev->driver); struct device *bridge; int ret = 0; @@ -1645,8 +1645,8 @@ static int pci_dma_configure(struct device *dev) pci_put_host_bridge_device(bridge); - /* @driver may not be valid when we're called from the IOMMU layer */ - if (!ret && dev->driver && !driver->driver_managed_dma) { + /* @drv may not be valid when we're called from the IOMMU layer */ + if (!ret && drv && !to_pci_driver(drv)->driver_managed_dma) { ret = iommu_device_use_default_domain(dev); if (ret) arch_teardown_dma_ops(dev); |