--- /dev/null
+From 15fffc6a5624b13b428bb1c6e9088e32a55eb82c Mon Sep 17 00:00:00 2001
+From: Dan Williams <dan.j.williams@intel.com>
+Date: Fri, 12 Jul 2024 12:42:09 -0700
+Subject: driver core: Fix uevent_show() vs driver detach race
+
+From: Dan Williams <dan.j.williams@intel.com>
+
+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.jp [1]
+Link: http://lore.kernel.org/669073b8ea479_5fffa294c1@dwillia2-xfh.jf.intel.com.notmuch
+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@dwillia2-xfh.jf.intel.com
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/base/core.c | 13 ++++++++-----
+ drivers/base/module.c | 4 ++++
+ 2 files changed, 12 insertions(+), 5 deletions(-)
+
+--- 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/swiotlb.h>
+@@ -2558,6 +2559,7 @@ static const char *dev_uevent_name(struc
+ static int dev_uevent(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 */
+@@ -2586,8 +2588,12 @@ static int dev_uevent(struct kobject *ko
+ 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);
+@@ -2657,11 +2663,8 @@ static ssize_t uevent_show(struct device
+ if (!env)
+ return -ENOMEM;
+
+- /* Synchronize with really_probe() */
+- device_lock(dev);
+ /* let the kset specific function add its keys */
+ retval = kset->uevent_ops->uevent(&dev->kobj, env);
+- device_unlock(dev);
+ if (retval)
+ goto out;
+
+--- 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_
+ if (!drv)
+ return;
+
++ /* Synchronize with dev_uevent() */
++ synchronize_rcu();
++
+ sysfs_remove_link(&drv->p->kobj, "module");
+
+ if (drv->owner)
--- /dev/null
+From 06c03c8edce333b9ad9c6b207d93d3a5ae7c10c0 Mon Sep 17 00:00:00 2001
+From: Justin Stitt <justinstitt@google.com>
+Date: Fri, 17 May 2024 00:47:10 +0000
+Subject: ntp: Safeguard against time_constant overflow
+
+From: Justin Stitt <justinstitt@google.com>
+
+commit 06c03c8edce333b9ad9c6b207d93d3a5ae7c10c0 upstream.
+
+Using syzkaller with the recently reintroduced signed integer overflow
+sanitizer produces this UBSAN report:
+
+UBSAN: signed-integer-overflow in ../kernel/time/ntp.c:738:18
+9223372036854775806 + 4 cannot be represented in type 'long'
+Call Trace:
+ handle_overflow+0x171/0x1b0
+ __do_adjtimex+0x1236/0x1440
+ do_adjtimex+0x2be/0x740
+
+The user supplied time_constant value is incremented by four and then
+clamped to the operating range.
+
+Before commit eea83d896e31 ("ntp: NTP4 user space bits update") the user
+supplied value was sanity checked to be in the operating range. That change
+removed the sanity check and relied on clamping after incrementing which
+does not work correctly when the user supplied value is in the overflow
+zone of the '+ 4' operation.
+
+The operation requires CAP_SYS_TIME and the side effect of the overflow is
+NTP getting out of sync.
+
+Similar to the fixups for time_maxerror and time_esterror, clamp the user
+space supplied value to the operating range.
+
+[ tglx: Switch to clamping ]
+
+Fixes: eea83d896e31 ("ntp: NTP4 user space bits update")
+Signed-off-by: Justin Stitt <justinstitt@google.com>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Cc: Miroslav Lichvar <mlichvar@redhat.com>
+Cc: stable@vger.kernel.org
+Link: https://lore.kernel.org/all/20240517-b4-sio-ntp-c-v2-1-f3a80096f36f@google.com
+Closes: https://github.com/KSPP/linux/issues/352
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/time/ntp.c | 5 ++---
+ 1 file changed, 2 insertions(+), 3 deletions(-)
+
+--- a/kernel/time/ntp.c
++++ b/kernel/time/ntp.c
+@@ -733,11 +733,10 @@ static inline void process_adjtimex_mode
+ time_esterror = clamp(txc->esterror, 0, NTP_PHASE_LIMIT);
+
+ if (txc->modes & ADJ_TIMECONST) {
+- time_constant = txc->constant;
++ time_constant = clamp(txc->constant, 0, MAXTC);
+ if (!(time_status & STA_NANO))
+ time_constant += 4;
+- time_constant = min(time_constant, (long)MAXTC);
+- time_constant = max(time_constant, 0l);
++ time_constant = clamp(time_constant, 0, MAXTC);
+ }
+
+ if (txc->modes & ADJ_TAI &&
projects / thirdparty / kernel / stable-queue.git / commitdiff
