From: Danilo Krummrich <dakr@kernel.org> stable inclusion from stable-v6.12.91 commit 4911b836f35c034c36f102db4ecbe339b38e7d1d category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15812 CVE: CVE-2026-53115 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 6c8dfb0362732bf1e4829867a2a5239fedc592d0 ] 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] Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> Acked-by: Ioana Ciornei <ioana.ciornei@nxp.com> Acked-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org> 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: 1f86a00c1159 ("bus/fsl-mc: add support for 'driver_override' in the mc-bus") Link: https://patch.msgid.link/20260324005919.2408620-3-dakr@kernel.org Signed-off-by: Danilo Krummrich <dakr@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Conflicts: drivers/bus/fsl-mc/fsl-mc-bus.c include/linux/fsl/mc.h [Context Conflicts] Signed-off-by: Lin Ruifeng <linruifeng4@huawei.com> --- drivers/bus/fsl-mc/fsl-mc-bus.c | 62 ++++--------------------------- drivers/vfio/fsl-mc/vfio_fsl_mc.c | 4 +- include/linux/fsl/mc.h | 2 - 3 files changed, 8 insertions(+), 60 deletions(-) diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c index 59389ad93595..12d32b86c4ab 100644 --- a/drivers/bus/fsl-mc/fsl-mc-bus.c +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c @@ -80,12 +80,16 @@ static int fsl_mc_bus_match(struct device *dev, struct device_driver *drv) struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(drv); bool found = false; + int ret; /* When driver_override is set, only bind to the matching driver */ - if (mc_dev->driver_override) { - found = !strcmp(mc_dev->driver_override, mc_drv->driver.name); + ret = device_match_driver_override(dev, drv); + if (ret > 0) { + found = true; goto out; } + if (ret == 0) + goto out; if (!mc_drv->match_id_table) goto out; @@ -156,58 +160,8 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(modalias); -static ssize_t driver_override_store(struct device *dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); - char *driver_override, *old = mc_dev->driver_override; - char *cp; - - if (WARN_ON(dev->bus != &fsl_mc_bus_type)) - return -EINVAL; - - if (count >= (PAGE_SIZE - 1)) - return -EINVAL; - - driver_override = kstrndup(buf, count, GFP_KERNEL); - if (!driver_override) - return -ENOMEM; - - cp = strchr(driver_override, '\n'); - if (cp) - *cp = '\0'; - - device_lock(dev); - if (strlen(driver_override)) { - mc_dev->driver_override = driver_override; - } else { - kfree(driver_override); - mc_dev->driver_override = NULL; - } - device_unlock(dev); - - kfree(old); - - return count; -} - -static ssize_t driver_override_show(struct device *dev, - struct device_attribute *attr, char *buf) -{ - struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); - ssize_t len; - - device_lock(dev); - len = snprintf(buf, PAGE_SIZE, "%s\n", mc_dev->driver_override); - device_unlock(dev); - return len; -} -static DEVICE_ATTR_RW(driver_override); - static struct attribute *fsl_mc_dev_attrs[] = { &dev_attr_modalias.attr, - &dev_attr_driver_override.attr, NULL, }; @@ -215,6 +169,7 @@ ATTRIBUTE_GROUPS(fsl_mc_dev); struct bus_type fsl_mc_bus_type = { .name = "fsl-mc", + .driver_override = true, .match = fsl_mc_bus_match, .uevent = fsl_mc_bus_uevent, .dma_configure = fsl_mc_dma_configure, @@ -823,9 +778,6 @@ EXPORT_SYMBOL_GPL(fsl_mc_device_add); */ void fsl_mc_device_remove(struct fsl_mc_device *mc_dev) { - kfree(mc_dev->driver_override); - mc_dev->driver_override = NULL; - /* * The device-specific remove callback will get invoked by device_del() */ diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c index 8722f5effacd..2187c3d99708 100644 --- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c @@ -524,9 +524,7 @@ static int vfio_fsl_mc_bus_notifier(struct notifier_block *nb, if (action == BUS_NOTIFY_ADD_DEVICE && vdev->mc_dev == mc_cont) { - mc_dev->driver_override = kasprintf(GFP_KERNEL, "%s", - vfio_fsl_mc_ops.name); - if (!mc_dev->driver_override) + if (device_set_driver_override(dev, vfio_fsl_mc_ops.name)) dev_warn(dev, "VFIO_FSL_MC: Setting driver override for device in dprc %s failed\n", dev_name(&mc_cont->dev)); else diff --git a/include/linux/fsl/mc.h b/include/linux/fsl/mc.h index db244874e834..41f293aee4c2 100644 --- a/include/linux/fsl/mc.h +++ b/include/linux/fsl/mc.h @@ -169,7 +169,6 @@ struct fsl_mc_obj_desc { * @regions: pointer to array of MMIO region entries * @irqs: pointer to array of pointers to interrupts allocated to this device * @resource: generic resource associated with this MC object device, if any. - * @driver_override: driver name to force a match * * Generic device object for MC object devices that are "attached" to a * MC bus. @@ -203,7 +202,6 @@ struct fsl_mc_device { struct fsl_mc_device_irq **irqs; struct fsl_mc_resource *resource; struct device_link *consumer_link; - char *driver_override; }; #define to_fsl_mc_device(_dev) \ -- 2.34.1