mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-11 00:42:56 -04:00
Code Issues Packages Projects Releases Wiki Activity

PCI: Fix driver_managed_dma check

Browse Source 
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: bcb81ac6ae ("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
This commit is contained in:
Robin Murphy
2025-04-25 14:39:29 +01:00
committed by Bjorn Helgaas
parent 19272b37aa
commit 78447d4545
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/pci/pci-driver.c
View File

@@ -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);