PCI: use generic driver_override infrastructure

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/
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")
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Alex Williamson <alex@shazbot.org>
Tested-by: Gui-Dong Han <hanguidong02@gmail.com>
Reviewed-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://patch.msgid.link/20260324005919.2408620-6-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index dd9075403987d84e068014b35745e8872e93fdae..d10ece0889f0f4f1d843c87040e116c89860af4c 100644 (file)
--- 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 16eaaf749ba9705580ccc2c5ac7154336f821c9b..a9006cf4e9c85063a7a418cbdb546d39509c5635 100644 (file)
--- 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 bccc7a4bdd794384b7877d453c7989941471c999..b4707640e1021ed6ac6ed6d0e29b9c89f9705838 100644 (file)
--- 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 d43745fe4c8433d11a6e605b03dc806e74a8d190..460852f79f29b97885f92b6d8d9625614d7e2b79 100644 (file)
--- 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 e4b27aecbf0591d6d62498924ad3a9af9e3fa34a..79a2b5dfd6941f9ccfc9a866926849b01b3d118a 100644 (file)
--- 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 1c270f1d512301de4d462fe7e5097c32af5c6f8d..57e9463e4347bc1398f51bbaede8f1b738342e8b 100644 (file)
--- 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[] */