Paul E. McKenney 3066820034 rcu: Reject RCU_LOCKDEP_WARN() false positives ... If another lockdep report runs concurrently with an RCU lockdep report from RCU_LOCKDEP_WARN(), the following sequence of events can occur: 1. debug_lockdep_rcu_enabled() sees that lockdep is enabled when called from (say) synchronize_rcu(). 2. Lockdep is disabled by a concurrent lockdep report. 3. debug_lockdep_rcu_enabled() evaluates its lockdep-expression argument, for example, lock_is_held(&rcu_bh_lock_map). 4. Because lockdep is now disabled, lock_is_held() plays it safe and returns the constant 1. 5. But in this case, the constant 1 is not safe, because invoking synchronize_rcu() under rcu_read_lock_bh() is disallowed. 6. debug_lockdep_rcu_enabled() wrongly invokes lockdep_rcu_suspicious(), resulting in a false-positive splat. This commit therefore changes RCU_LOCKDEP_WARN() to check debug_lockdep_rcu_enabled() after checking the lockdep expression, so that any "safe" returns from lock_is_held() are rejected by debug_lockdep_rcu_enabled(). This requires memory ordering, which is supplied by READ_ONCE(debug_locks). The resulting volatile accesses prevent the compiler from reordering and the fact that only one variable is being accessed prevents the underlying hardware from reordering. The combination works for IA64, which can reorder reads to the same location, but this is defeated by the volatile accesses, which compile to load instructions that provide ordering. Reported-by: syzbot+dde0cc33951735441301@syzkaller.appspotmail.com Reported-by: Matthew Wilcox <willy@infradead.org> Reported-by: syzbot+88e4f02896967fe1ab0d@syzkaller.appspotmail.com Reported-by: Thomas Gleixner <tglx@linutronix.de> Suggested-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>		2021-05-10 16:22:54 -07:00
..
bpf	bpf: Fix leakage of uninitialized bpf stack under speculation	2021-05-03 11:56:23 +02:00
cgroup	cgroup: rstat: punt root-level optimization to individual controllers	2021-04-30 11:20:37 -07:00
configs	drivers/char: remove /dev/kmem for good	2021-05-07 00:26:34 -07:00
debug	printk changes for 5.13	2021-04-27 18:09:44 -07:00
dma	Merge branch 'stable/for-linus-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb	2021-05-04 10:58:49 -07:00
entry	A trivial cleanup of typo fixes.	2021-04-26 09:41:15 -07:00
events	ARM:	2021-05-01 10:14:08 -07:00
gcov	gcov: clang: drop support for clang-10 and older	2021-05-07 00:26:32 -07:00
irq	gpio updates for v5.13	2021-05-05 12:39:29 -07:00
kcsan	kcsan: Fix printk format string	2021-04-22 14:36:03 +02:00
livepatch	Livepatching changes for 5.13	2021-04-27 18:14:38 -07:00
locking	lockdep: Explicitly flag likely false-positive report	2021-05-10 16:22:54 -07:00
power	PM: sleep: fix typos in comments	2021-04-08 19:37:21 +02:00
printk	kernel/printk.c: Fixed mundane typos	2021-03-30 15:34:17 +02:00
rcu	rcu: Reject RCU_LOCKDEP_WARN() false positives	2021-05-10 16:22:54 -07:00
sched	sched/fair: Fix unfairness caused by missing load decay	2021-05-06 15:33:27 +02:00
time	ARM:	2021-05-01 10:14:08 -07:00
trace	tracing: Fix probes written to the set_ftrace_filter file	2021-05-06 10:03:38 -07:00
.gitignore	.gitignore: prefix local generated files with a slash	2021-05-02 00:43:35 +09:00
acct.c	kernel/acct.c: use #elif instead of #end and #elif	2020-12-15 22:46:15 -08:00
async.c	kernel/async.c: remove async_unregister_domain()	2021-05-07 00:26:33 -07:00
audit_fsnotify.c	audit_alloc_mark(): don't open-code ERR_CAST()	2021-02-23 10:25:27 -05:00
audit_tree.c	fsnotify: generalize handle_inode_event()	2020-12-03 14:58:35 +01:00
audit_watch.c	fsnotify: generalize handle_inode_event()	2020-12-03 14:58:35 +01:00
audit.c	lsm: separate security_task_getsecid() into subjective and objective variants	2021-03-22 15:23:32 -04:00
audit.h	audit: avoid -Wempty-body warning	2021-03-24 12:11:48 -04:00
auditfilter.c	lsm: separate security_task_getsecid() into subjective and objective variants	2021-03-22 15:23:32 -04:00
auditsc.c	audit/stable-5.13 PR 20210426	2021-04-27 13:50:58 -07:00
backtracetest.c
bounds.c
capability.c	capability: handle idmapped mounts	2021-01-24 14:27:16 +01:00
cfi.c	add support for Clang CFI	2021-04-08 16:04:20 -07:00
compat.c
configs.c
context_tracking.c
cpu_pm.c
cpu.c	cpumask/hotplug: Fix cpu_dying() state tracking	2021-04-21 13:55:43 +02:00
crash_core.c	kdump: append uts_namespace.name offset to VMCOREINFO	2020-12-15 22:46:18 -08:00
crash_dump.c
cred.c	kernel/cred.c: make init_groups static	2021-05-06 19:24:11 -07:00
delayacct.c
dma.c
exec_domain.c
exit.c	do_wait: make PIDTYPE_PID case O(1) instead of O(n)	2021-05-06 19:24:13 -07:00
extable.c
fail_function.c	fault-injection: handle EI_ETYPE_TRUE	2020-12-15 22:46:19 -08:00
fork.c	kernel/fork.c: fix typos	2021-05-06 19:24:13 -07:00
freezer.c	Revert "kernel: freezer should treat PF_IO_WORKER like PF_KTHREAD for freezing"	2021-03-27 14:09:10 -06:00
futex.c	futex: Make syscall entry points less convoluted	2021-05-06 20:19:04 +02:00
gen_kheaders.sh	kbuild: redo fake deps at include/config/*.h	2021-04-25 05:26:10 +09:00
groups.c	groups: simplify struct group_info allocation	2021-02-26 09:41:03 -08:00
hung_task.c
iomem.c
irq_work.c	irq_work: record irq_work_queue() call stack	2021-04-30 11:20:42 -07:00
jump_label.c	static_call: Fix static_call_update() sanity check	2021-03-19 13:16:44 +01:00
kallsyms.c	kallsyms: strip ThinLTO hashes from static functions	2021-04-08 16:04:21 -07:00
kcmp.c	Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:36:48 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt	preempt: Introduce CONFIG_PREEMPT_DYNAMIC	2021-02-17 14:12:24 +01:00
kcov.c
kexec_core.c	kexec: dump kmessage before machine_kexec	2021-05-07 00:26:32 -07:00
kexec_elf.c
kexec_file.c	kernel: kexec_file: fix error return code of kexec_calculate_store_digests()	2021-05-07 00:26:32 -07:00
kexec_internal.h	kexec: move machine_kexec_post_load() to public interface	2021-02-22 12:33:26 +00:00
kexec.c
kheaders.c
kmod.c	modules: add CONFIG_MODPROBE_PATH	2021-05-07 00:26:33 -07:00
kprobes.c	kprobes: Fix to delay the kprobes jump optimization	2021-02-19 14:57:12 -05:00
ksysfs.c
kthread.c	Scheduler updates for this cycle are:	2021-04-28 13:33:57 -07:00
latencytop.c
Makefile	kbuild: update config_data.gz only when the content of .config is changed	2021-05-02 00:43:35 +09:00
module_signature.c	module: harden ELF info handling	2021-01-19 10:24:45 +01:00
module_signing.c	module: harden ELF info handling	2021-01-19 10:24:45 +01:00
module-internal.h
module.c	Summary of modules changes for the 5.13 merge window:	2021-04-30 12:29:36 -07:00
notifier.c
nsproxy.c	fixes-v5.11	2020-12-14 16:40:27 -08:00
padata.c
panic.c	panic: don't dump stack twice on warn	2020-11-14 11:26:04 -08:00
params.c	Modules updates for v5.11	2020-12-17 13:01:31 -08:00
pid_namespace.c	fixes-v5.11	2020-12-14 16:40:27 -08:00
pid.c	Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2020-12-15 19:36:48 -08:00
profile.c	kernel: Initialize cpumask before parsing	2021-04-10 13:35:54 +02:00
ptrace.c	Linux 5.12-rc8	2021-04-20 10:13:58 +02:00
range.c
reboot.c	Revert "PM: ACPI: reboot: Use S5 for reboot"	2021-03-18 16:58:02 +01:00
regset.c
relay.c	relay: allow the use of const callback structs	2020-12-15 22:46:18 -08:00
resource_kunit.c	resource: provide meaningful MODULE_LICENSE() in test suite	2020-11-25 18:52:35 +01:00
resource.c	kernel/resource: fix locking in request_free_mem_region	2021-05-07 00:26:33 -07:00
rseq.c	rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs()	2021-04-14 18:04:09 +02:00
scftorture.c	scftorture: Add debug output for wrong-CPU warning	2021-01-04 13:53:41 -08:00
scs.c	scs: switch to vmapped shadow stacks	2020-12-01 10:30:28 +00:00
seccomp.c	Merge branch 'work.file' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2021-05-03 11:05:28 -07:00
signal.c	Scheduler updates for this cycle are:	2021-04-28 13:33:57 -07:00
smp.c	smp: Fix smp_call_function_single_async prototype	2021-05-06 15:33:49 +02:00
smpboot.c	kthread: Extract KTHREAD_IS_PER_CPU	2021-01-22 15:09:42 +01:00
smpboot.h
softirq.c	RCU changes for this cycle were:	2021-04-28 12:00:13 -07:00
stackleak.c
stacktrace.c
static_call.c	static_call: Fix unused variable warn w/o MODULE	2021-04-09 13:22:12 +02:00
stop_machine.c	stop_machine: Add caller debug info to queue_stop_cpus_work	2021-03-23 16:01:58 +01:00
sys_ni.c	Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com>	2021-05-01 18:50:44 -07:00
sys.c	kernel/sys.c: fix typo	2021-05-07 00:26:34 -07:00
sysctl-test.c
sysctl.c	mm/compaction: remove unused variable sysctl_compact_memory	2021-05-05 11:27:24 -07:00
task_work.c	kasan: record task_work_add() call stack	2021-04-30 11:20:42 -07:00
taskstats.c	treewide: rename nla_strlcpy to nla_strscpy.	2020-11-16 08:08:54 -08:00
test_kprobes.c
torture.c	torture: Replace torture_init_begin string with %s	2021-03-08 14:22:28 -08:00
tracepoint.c	tracepoints: Code clean up	2021-02-09 12:27:29 -05:00
tsacct.c
ucount.c	fanotify: configurable limits via sysfs	2021-03-16 16:49:31 +01:00
uid16.c
uid16.h
umh.c	kernel/umh.c: fix some spelling mistakes	2021-05-07 00:26:34 -07:00
up.c	A set of locking related fixes and updates:	2021-05-09 13:07:03 -07:00
user_namespace.c	kernel/user_namespace.c: fix typos	2021-05-07 00:26:34 -07:00
user-return-notifier.c
user.c
usermode_driver.c	bpf: Fix umd memory leak in copy_process()	2021-03-19 22:23:19 +01:00
utsname_sysctl.c
utsname.c
watch_queue.c	watch_queue: rectify kernel-doc for init_watch()	2021-01-26 11:16:34 +00:00
watchdog_hld.c
watchdog.c	watchdog: cleanup handling of false positives	2021-04-30 11:20:36 -07:00
workqueue_internal.h
workqueue.c	CFI on arm64 series for v5.13-rc1	2021-04-27 10:16:46 -07:00