[PATCH 05/12] PCI: use generic driver_override infrastructure

Danilo Krummrich
2026-03-24T01:00:20Z

When a driver is probed through __driver_attach(), the bus' match()
callback is called without the device lock held, thus accessing the
driver_override field without a lock, which can cause a UAF.

Fix this by using the driver-core driver_override infrastructure taking
care of proper locking internally.

Note that calling match() from __driver_attach() without the device lock
held is intentional. [1]

Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [1]
Reported-by: Gui-Dong Han <hanguidong02@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789
Fixes: 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
drivers/pci/pci-driver.c | 11 +++++++----
drivers/pci/pci-sysfs.c | 28 ----------------------------
drivers/pci/probe.c | 1 -
drivers/vfio/pci/vfio_pci_core.c | 5 ++---
drivers/xen/xen-pciback/pci_stub.c | 6 ++++--
include/linux/pci.h | 6 ------
6 files changed, 13 insertions(+), 44 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index dd9075403987..d10ece0889f0 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -138,9 +138,11 @@ static const struct pci_device_id *pci_match_device(struct pci_driver *drv,
{
struct pci_dynid *dynid;
const struct pci_device_id *found_id = NULL, *ids;
+ int ret;

/* When driver_override is set, only bind to the matching driver */
- if (dev->driver_override && strcmp(dev->driver_override, drv->name))
+ ret = device_match_driver_override(&dev->dev, &drv->driver);
+ if (ret == 0)
return NULL;

/* Look at the dynamic ids first, before the static ones */
@@ -164,7 +166,7 @@ static const struct pci_device_id *pci_match_device(struct pci_driver *drv,
* matching.
*/
if (found_id->override_only) {
- if (dev->driver_override)
+ if (ret > 0)
return found_id;
} else {
return found_id;
@@ -172,7 +174,7 @@ static const struct pci_device_id *pci_match_device(struct pci_driver *drv,
}

/* driver_override will always match, send a dummy id */
- if (dev->driver_override)
+ if (ret > 0)
return &pci_device_id_any;
return NULL;
}
@@ -452,7 +454,7 @@ static int __pci_device_probe(struct pci_driver *drv, struct pci_dev *pci_dev)
static inline bool pci_device_can_probe(struct pci_dev *pdev)
{
return (!pdev->is_virtfn || pdev->physfn->sriov->drivers_autoprobe ||
- pdev->driver_override);
+ device_has_driver_override(&pdev->dev));
}
#else
static inline bool pci_device_can_probe(struct pci_dev *pdev)
@@ -1722,6 +1724,7 @@ static const struct cpumask *pci_device_irq_get_affinity(struct device *dev,

const struct bus_type pci_bus_type = {
.name = "pci",
+ .driver_override = true,
.match = pci_bus_match,
.uevent = pci_uevent,
.probe = pci_device_probe,
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 16eaaf749ba9..a9006cf4e9c8 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -615,33 +615,6 @@ static ssize_t devspec_show(struct device *dev,
static DEVICE_ATTR_RO(devspec);
#endif

-static ssize_t driver_override_store(struct device *dev,
- struct device_attribute *attr,
- const char *buf, size_t count)
-{
- struct pci_dev *pdev = to_pci_dev(dev);
- int ret;
-
- ret = driver_set_override(dev, &pdev->driver_override, buf, count);
- if (ret)
- return ret;
-
- return count;
-}
-
-static ssize_t driver_override_show(struct device *dev,
- struct device_attribute *attr, char *buf)
-{
- struct pci_dev *pdev = to_pci_dev(dev);
- ssize_t len;
-
- device_lock(dev);
- len = sysfs_emit(buf, "%s\n", pdev->driver_override);
- device_unlock(dev);
- return len;
-}
-static DEVICE_ATTR_RW(driver_override);
-
static struct attribute *pci_dev_attrs[] = {
&dev_attr_power_state.attr,
&dev_attr_resource.attr,
@@ -669,7 +642,6 @@ static struct attribute *pci_dev_attrs[] = {
#ifdef CONFIG_OF
&dev_attr_devspec.attr,
#endif
- &dev_attr_driver_override.attr,
&dev_attr_ari_enabled.attr,
NULL,
};
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index bccc7a4bdd79..b4707640e102 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2488,7 +2488,6 @@ static void pci_release_dev(struct device *dev)
pci_release_of_node(pci_dev);
pcibios_release_device(pci_dev);
pci_bus_put(pci_dev->bus);
- kfree(pci_dev->driver_override);
bitmap_free(pci_dev->dma_alias_mask);
dev_dbg(dev, "device released\n");
kfree(pci_dev);
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index d43745fe4c84..460852f79f29 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1987,9 +1987,8 @@ static int vfio_pci_bus_notifier(struct notifier_block *nb,
pdev->is_virtfn && physfn == vdev->pdev) {
pci_info(vdev->pdev, "Captured SR-IOV VF %s driver_override\n",
pci_name(pdev));
- pdev->driver_override = kasprintf(GFP_KERNEL, "%s",
- vdev->vdev.ops->name);
- WARN_ON(!pdev->driver_override);
+ WARN_ON(device_set_driver_override(&pdev->dev,
+ vdev->vdev.ops->name));
} else if (action == BUS_NOTIFY_BOUND_DRIVER &&
pdev->is_virtfn && physfn == vdev->pdev) {
struct pci_driver *drv = pci_dev_driver(pdev);
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index e4b27aecbf05..79a2b5dfd694 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -598,6 +598,8 @@ static int pcistub_seize(struct pci_dev *dev,
return err;
}

+static struct pci_driver xen_pcibk_pci_driver;
+
/* Called when 'bind'. This means we must _NOT_ call pci_reset_function or
* other functions that take the sysfs lock. */
static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
@@ -609,8 +611,8 @@ static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)

match = pcistub_match(dev);

- if ((dev->driver_override &&
- !strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) ||
+ if (device_match_driver_override(&dev->dev,
+ &xen_pcibk_pci_driver.driver) > 0 ||
match) {

if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 1c270f1d5123..57e9463e4347 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -575,12 +575,6 @@ struct pci_dev {
u8 supported_speeds; /* Supported Link Speeds Vector */
phys_addr_t rom; /* Physical address if not from BAR */
size_t romlen; /* Length if not from BAR */
- /*
- * Driver name to force a match. Do not set directly, because core
- * frees it. Use driver_set_override() to set or clear it.
- */
- const char *driver_override;
-
unsigned long priv_flags; /* Private flags for the PCI driver */

/* These methods index pci_reset_fn_methods[] */
--
2.53.0