From: Dirk Behme dirk.behme@de.bosch.com

stable inclusion from stable-v5.10.221 commit 760603e30bf19d7b4c28e9d81f18b54fa3b745ad category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACSAA CVE: CVE-2024-39501

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

commit c0a40097f0bc81deafc15f9195d1fb54595cd6d0 upstream.

Synchronize the dev->driver usage in really_probe() and dev_uevent(). These can run in different threads, what can result in the following race condition for dev->driver uninitialization:

Thread #1: ==========

really_probe() { ... probe_failed: ... device_unbind_cleanup(dev) { ... dev->driver = NULL; // <= Failed probe sets dev->driver to NULL ... } ... }

Thread #2: ==========

dev_uevent() { ... if (dev->driver) // If dev->driver is NULLed from really_probe() from here on, // after above check, the system crashes add_uevent_var(env, "DRIVER=%s", dev->driver->name); ... }

really_probe() holds the lock, already. So nothing needs to be done there. dev_uevent() is called with lock held, often, too. But not always. What implies that we can't add any locking in dev_uevent() itself. So fix this race by adding the lock to the non-protected path. This is the path where above race is observed:

dev_uevent+0x235/0x380 uevent_show+0x10c/0x1f0 <= Add lock here dev_attr_show+0x3a/0xa0 sysfs_kf_seq_show+0x17c/0x250 kernfs_seq_show+0x7c/0x90 seq_read_iter+0x2d7/0x940 kernfs_fop_read_iter+0xc6/0x310 vfs_read+0x5bc/0x6b0 ksys_read+0xeb/0x1b0 __x64_sys_read+0x42/0x50 x64_sys_call+0x27ad/0x2d30 do_syscall_64+0xcd/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Similar cases are reported by syzkaller in

https://syzkaller.appspot.com/bug?extid=ffa8143439596313a85a

But these are regarding the *initialization* of dev->driver

dev->driver = drv;

As this switches dev->driver to non-NULL these reports can be considered to be false-positives (which should be "fixed" by this commit, as well, though).

The same issue was reported and tried to be fixed back in 2015 in

https://lore.kernel.org/lkml/1421259054-2574-1-git-send-email-a.sangwan@sams...

already.

Fixes: 239378f16aa1 ("Driver core: add uevent vars for devices of a class") Cc: stable stable@kernel.org Cc: syzbot+ffa8143439596313a85a@syzkaller.appspotmail.com Cc: Ashish Sangwan a.sangwan@samsung.com Cc: Namjae Jeon namjae.jeon@samsung.com Signed-off-by: Dirk Behme dirk.behme@de.bosch.com Link: https://lore.kernel.org/r/20240513050634.3964461-1-dirk.behme@de.bosch.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com --- drivers/base/core.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c index 82b50a89cedc..a5ff2a88bbeb 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2041,8 +2041,11 @@ static ssize_t uevent_show(struct device *dev, struct device_attribute *attr, if (!env) return -ENOMEM;

+ /* Synchronize with really_probe() */ + device_lock(dev); /* let the kset specific function add its keys */ retval = kset->uevent_ops->uevent(kset, &dev->kobj, env); + device_unlock(dev); if (retval) goto out;

From: Dan Williams dan.j.williams@intel.com

stable inclusion from stable-v5.10.224 commit f098e8fc7227166206256c18d56ab622039108b1 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACSAA CVE: CVE-2024-39501

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

--------------------------------

commit 15fffc6a5624b13b428bb1c6e9088e32a55eb82c upstream.

uevent_show() wants to de-reference dev->driver->name. There is no clean way for a device attribute to de-reference dev->driver unless that attribute is defined via (struct device_driver).dev_groups. Instead, the anti-pattern of taking the device_lock() in the attribute handler risks deadlocks with code paths that remove device attributes while holding the lock.

This deadlock is typically invisible to lockdep given the device_lock() is marked lockdep_set_novalidate_class(), but some subsystems allocate a local lockdep key for @dev->mutex to reveal reports of the form:

====================================================== WARNING: possible circular locking dependency detected 6.10.0-rc7+ #275 Tainted: G OE N ------------------------------------------------------ modprobe/2374 is trying to acquire lock: ffff8c2270070de0 (kn->active#6){++++}-{0:0}, at: __kernfs_remove+0xde/0x220

but task is already holding lock: ffff8c22016e88f8 (&cxl_root_key){+.+.}-{3:3}, at: device_release_driver_internal+0x39/0x210

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&cxl_root_key){+.+.}-{3:3}: __mutex_lock+0x99/0xc30 uevent_show+0xac/0x130 dev_attr_show+0x18/0x40 sysfs_kf_seq_show+0xac/0xf0 seq_read_iter+0x110/0x450 vfs_read+0x25b/0x340 ksys_read+0x67/0xf0 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e

-> #0 (kn->active#6){++++}-{0:0}: __lock_acquire+0x121a/0x1fa0 lock_acquire+0xd6/0x2e0 kernfs_drain+0x1e9/0x200 __kernfs_remove+0xde/0x220 kernfs_remove_by_name_ns+0x5e/0xa0 device_del+0x168/0x410 device_unregister+0x13/0x60 devres_release_all+0xb8/0x110 device_unbind_cleanup+0xe/0x70 device_release_driver_internal+0x1c7/0x210 driver_detach+0x47/0x90 bus_remove_driver+0x6c/0xf0 cxl_acpi_exit+0xc/0x11 [cxl_acpi] __do_sys_delete_module.isra.0+0x181/0x260 do_syscall_64+0x75/0x190 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The observation though is that driver objects are typically much longer lived than device objects. It is reasonable to perform lockless de-reference of a @driver pointer even if it is racing detach from a device. Given the infrequency of driver unregistration, use synchronize_rcu() in module_remove_driver() to close any potential races. It is potentially overkill to suffer synchronize_rcu() just to handle the rare module removal racing uevent_show() event.

Thanks to Tetsuo Handa for the debug analysis of the syzbot report [1].

Fixes: c0a40097f0bc ("drivers: core: synchronize really_probe() and dev_uevent()") Reported-by: syzbot+4762dd74e32532cda5ff@syzkaller.appspotmail.com Reported-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Closes: http://lore.kernel.org/5aa5558f-90a4-4864-b1b1-5d6784c5607d@I-love.SAKURA.ne... [1] Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.no... Cc: stable@vger.kernel.org Cc: Ashish Sangwan a.sangwan@samsung.com Cc: Namjae Jeon namjae.jeon@samsung.com Cc: Dirk Behme dirk.behme@de.bosch.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Rafael J. Wysocki rafael@kernel.org Signed-off-by: Dan Williams dan.j.williams@intel.com Link: https://lore.kernel.org/r/172081332794.577428.9738802016494057132.stgit@dwil... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Chen Jun chenjun102@huawei.com --- drivers/base/core.c | 13 ++++++++----- drivers/base/module.c | 4 ++++ 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c index a5ff2a88bbeb..d3e6ce014ec2 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -25,6 +25,7 @@ #include <linux/mutex.h> #include <linux/pm_runtime.h> #include <linux/netdevice.h> +#include <linux/rcupdate.h> #include <linux/sched/signal.h> #include <linux/sched/mm.h> #include <linux/sysfs.h> @@ -1942,6 +1943,7 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj, struct kobj_uevent_env *env) { struct device *dev = kobj_to_dev(kobj); + struct device_driver *driver; int retval = 0;

/* add device node properties if present */ @@ -1970,8 +1972,12 @@ static int dev_uevent(struct kset *kset, struct kobject *kobj, if (dev->type && dev->type->name) add_uevent_var(env, "DEVTYPE=%s", dev->type->name);

- if (dev->driver) - add_uevent_var(env, "DRIVER=%s", dev->driver->name); + /* Synchronize with module_remove_driver() */ + rcu_read_lock(); + driver = READ_ONCE(dev->driver); + if (driver) + add_uevent_var(env, "DRIVER=%s", driver->name); + rcu_read_unlock();

/* Add common DT information about the device */ of_device_uevent(dev, env); @@ -2041,11 +2047,8 @@ static ssize_t uevent_show(struct device *dev, struct device_attribute *attr, if (!env) return -ENOMEM;

- /* Synchronize with really_probe() */ - device_lock(dev); /* let the kset specific function add its keys */ retval = kset->uevent_ops->uevent(kset, &dev->kobj, env); - device_unlock(dev); if (retval) goto out;

diff --git a/drivers/base/module.c b/drivers/base/module.c index 46ad4d636731..851cc5367c04 100644 --- a/drivers/base/module.c +++ b/drivers/base/module.c @@ -7,6 +7,7 @@ #include <linux/errno.h> #include <linux/slab.h> #include <linux/string.h> +#include <linux/rcupdate.h> #include "base.h"

static char *make_driver_name(struct device_driver *drv) @@ -77,6 +78,9 @@ void module_remove_driver(struct device_driver *drv) if (!drv) return;

+ /* Synchronize with dev_uevent() */ + synchronize_rcu(); + sysfs_remove_link(&drv->p->kobj, "module");

if (drv->owner)