Rusty Russell d6692b5c5d modules: fix longstanding /proc/kallsyms vs module insertion race. ... commit 8244062ef1e54502ef55f54cced659913f244c3e upstream. For CONFIG_KALLSYMS, we keep two symbol tables and two string tables. There's one full copy, marked SHF_ALLOC and laid out at the end of the module's init section. There's also a cut-down version that only contains core symbols and strings, and lives in the module's core section. After module init (and before we free the module memory), we switch the mod->symtab, mod->num_symtab and mod->strtab to point to the core versions. We do this under the module_mutex. However, kallsyms doesn't take the module_mutex: it uses preempt_disable() and rcu tricks to walk through the modules, because it's used in the oops path. It's also used in /proc/kallsyms. There's nothing atomic about the change of these variables, so we can get the old (larger!) num_symtab and the new symtab pointer; in fact this is what I saw when trying to reproduce. By grouping these variables together, we can use a carefully-dereferenced pointer to ensure we always get one or the other (the free of the module init section is already done in an RCU callback, so that's safe). We allocate the init one at the end of the module init section, and keep the core one inside the struct module itself (it could also have been allocated at the end of the module core, but that's probably overkill). [ Rebased for 4.4-stable and older, because the following changes aren't in the older trees: - e0224418516b4d8a6c2160574bac18447c354ef0: adds arg to is_core_symbol - 7523e4dc5057e157212b4741abd6256e03404cf1: module_init/module_core/init_size/core_size become init_layout.base/core_layout.base/init_layout.size/core_layout.size. Original commit: 8244062ef1e54502ef55f54cced659913f244c3e ] Reported-by: Weilong Chen <chenweilong@huawei.com> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111541 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2016-03-16 08:41:37 -07:00
..
cpu	sched, idle: Fix the idle polling state logic	2013-11-29 11:11:42 -08:00
debug	kdb: fix incorrect counts in KDB summary command output	2015-03-06 14:40:52 -08:00
events	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 11:57:47 -08:00
gcov
irq	genirq: Prevent chip buslock deadlock	2016-03-03 15:06:20 -08:00
power	PM / QoS: remove duplicate call to pm_qos_update_target	2015-03-18 13:22:28 +01:00
sched	sched/core: Remove false-positive warning from wake_up_process()	2016-03-03 15:06:22 -08:00
time	posix-clock: Fix return code on the poll method's error path	2016-03-03 15:06:23 -08:00
trace	tracing: Fix showing function event in available_events	2016-03-03 15:06:24 -08:00
.gitignore	kernel/hz.bc: ignore.	2013-04-22 07:09:06 -07:00
acct.c	fs: Fix hang with BSD accounting on frozen filesystem	2013-05-04 14:57:58 -04:00
async.c
audit.c	CAPABILITIES: remove undefined caps from all processes	2014-09-17 09:03:57 -07:00
audit.h	audit: fix mq_open and mq_unlink to add the MQ root as a hidden parent audit_names record	2013-12-04 10:57:03 -08:00
audit_tree.c	audit: keep inode pinned	2014-11-21 09:22:52 -08:00
audit_watch.c
auditfilter.c	auditfilter.c: fix kernel-doc warnings	2013-05-24 16:22:52 -07:00
auditsc.c	auditsc: audit_krule mask accesses need bounds checking	2014-06-16 13:42:53 -07:00
backtracetest.c
bounds.c
capability.c	CAPABILITIES: remove undefined caps from all processes	2014-09-17 09:03:57 -07:00
cgroup.c	move d_rcu from overlapping d_child to overlapping d_alias	2015-04-29 10:34:00 +02:00
cgroup_freezer.c
compat.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal	2013-05-01 07:21:43 -07:00
configs.c	proc: Supply PDE attribute setting accessor functions	2013-05-01 17:29:18 -04:00
context_tracking.c	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-06-20 08:18:35 -10:00
cpu.c	sched: Fix hotplug vs. set_cpus_allowed_ptr()	2014-06-11 12:03:24 -07:00
cpu_pm.c
cpuset.c	cpuset,mempolicy: fix sleeping function called from invalid context	2014-07-17 15:58:00 -07:00
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	introduce for_each_thread() to replace the buggy while_each_thread()	2014-10-05 14:54:15 -07:00
extable.c	extable: Flip the sorting message	2013-04-15 13:25:16 +02:00
fork.c	unshare: Unsharing a thread does not require unsharing a vm	2015-10-01 12:07:28 +02:00
freezer.c	freezer: Do not freeze tasks killed by OOM killer	2014-11-14 08:47:58 -08:00
futex.c	futex: Drop refcount if requeue_pi() acquired the rtmutex	2016-02-25 11:57:49 -08:00
futex_compat.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 11:57:47 -08:00
groups.c	userns: Don't allow setgroups until a gid mapping has been setablished	2015-01-08 09:58:16 -08:00
hrtimer.c	hrtimer: Set expiry time before switch_hrtimer_base()	2014-06-07 13:25:31 -07:00
hung_task.c
irq_work.c
itimer.c
jump_label.c
kallsyms.c	kernel: kallsyms: memory override issue, need check destination buffer length	2013-04-15 15:17:26 +09:30
kcmp.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 11:57:47 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks	locking/mutex: Disable optimistic spinning on some architectures	2014-07-28 08:00:07 -07:00
Kconfig.preempt
kexec.c	PCI: Disable Bus Master only on kexec reboot	2013-12-20 07:45:08 -08:00
kmod.c	usermodehelper: check subprocess_info->path != NULL	2013-05-16 12:01:11 -07:00
kprobes.c	kprobes: Fix to free gone and unused optprobes	2013-05-28 10:37:59 +02:00
ksysfs.c
kthread.c	kthread: implement probe_kthread_data()	2013-04-30 17:04:02 -07:00
latencytop.c
lglock.c
lockdep.c	Merge branch 'for-3.10/drivers' of git://git.kernel.dk/linux-block	2013-05-08 11:51:05 -07:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
Makefile	We get rid of the general module prefix confusion with a binary config option,	2013-05-05 10:58:06 -07:00
modsign_certificate.S	CONFIG_SYMBOL_PREFIX: cleanup.	2013-03-15 15:09:43 +10:30
modsign_pubkey.c
module-internal.h
module.c	modules: fix longstanding /proc/kallsyms vs module insertion race.	2016-03-16 08:41:37 -07:00
module_signing.c
mutex-debug.c
mutex-debug.h
mutex.c	mutex: Back out architecture specific check for negative mutex count	2013-04-19 09:33:36 +02:00
mutex.h
notifier.c
nsproxy.c	proc: Split the namespace stuff out into linux/proc_ns.h	2013-05-01 17:29:39 -04:00
padata.c
panic.c	dump_stack: implement arch-specific hardware description in task dumps	2013-04-30 17:04:02 -07:00
params.c	params: Fix potential memory leak in add_sysfs_param()	2013-03-18 11:40:21 +00:00
pid.c	exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting	2015-01-08 09:58:17 -08:00
pid_namespace.c	pid_namespace: pidns_get() should check task_active_pid_ns() != NULL	2014-04-26 17:15:34 -07:00
posix-cpu-timers.c	posix_timers: Fix pre-condition to stop the tick on full dynticks	2013-04-22 19:59:25 +02:00
posix-timers.c	posix-timers: Fix stack info leak in timer_create()	2014-11-14 08:48:00 -08:00
printk.c	console: Fix console name size mismatch	2015-04-19 10:10:51 +02:00
profile.c	proc: Supply PDE attribute setting accessor functions	2013-05-01 17:29:18 -04:00
ptrace.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 11:57:47 -08:00
range.c	range: Do not add new blank slot with add_range_with_merge	2013-06-18 11:32:10 -05:00
rcu.h
rcupdate.c
rcutiny.c
rcutiny_plugin.h
rcutorture.c
rcutree.c	rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration	2013-06-10 13:37:12 -07:00
rcutree.h	rcu: Don't call wakeup() with rcu_node structure ->lock held	2013-06-10 13:37:11 -07:00
rcutree_plugin.h	rcu: Don't allocate bootmem from rcu_init()	2013-05-15 10:41:12 -07:00
rcutree_trace.c	rcutrace: single_open() leaks	2013-05-05 00:16:35 -04:00
relay.c	Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block	2013-05-08 10:13:35 -07:00
res_counter.c
resource.c	kernel/resource.c: fix muxed resource handling in __request_region()	2016-03-03 15:06:24 -08:00
rtmutex-debug.c
rtmutex-debug.h	rtmutex: Handle deadlock detection smarter	2014-07-17 15:58:04 -07:00
rtmutex-tester.c	locking/rtmutex/tester: Set correct permissions on sysfs files	2013-04-10 14:48:37 +02:00
rtmutex.c	rtmutex: Plug slow unlock race	2014-07-17 15:58:04 -07:00
rtmutex.h	rtmutex: Handle deadlock detection smarter	2014-07-17 15:58:04 -07:00
rtmutex_common.h
rwsem.c	Revert "rw_semaphore: remove up/down_read_non_owner"	2013-03-23 15:53:52 -07:00
seccomp.c	seccomp: allow BPF_XOR based ALU instructions.	2013-03-26 11:07:19 +11:00
semaphore.c	semaphore: use `bool' type for semaphore_waiter's up	2013-04-30 17:04:08 -07:00
signal.c	kernel/signal.c: unexport sigsuspend()	2016-02-19 14:22:37 -08:00
smp.c	kernel/smp.c:on_each_cpu_cond(): fix warning in fallback path	2014-09-17 09:03:57 -07:00
smpboot.c	smpboot: Add missing get_online_cpus() in smpboot_register_percpu_thread()	2015-02-11 14:48:17 +08:00
smpboot.h
softirq.c	revert "softirq: Add support for triggering softirq work on softirqs"	2015-05-17 09:51:33 -07:00
spinlock.c
srcu.c
stacktrace.c
stop_machine.c
sys.c	reboot: rigrate shutdown/reboot to boot cpu	2013-06-12 16:29:44 -07:00
sys_ni.c	unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE	2013-05-09 13:46:38 -04:00
sysctl.c	perf: Enforce 1 as lower limit for perf_event_max_sample_rate	2014-06-11 12:03:27 -07:00
sysctl_binary.c	switch compat_sys_sysctl to COMPAT_SYSCALL_DEFINE	2013-05-09 14:53:20 -04:00
task_work.c
taskstats.c
test_kprobes.c	kernel/: rename random32() to prandom_u32()	2013-04-29 18:28:42 -07:00
time.c	time: settimeofday: Validate the values of tv from user	2015-01-29 17:40:56 -08:00
timeconst.bc
timer.c	timer: Prevent overflow in apply_slack	2014-06-07 13:25:30 -07:00
tracepoint.c	tracepoint: Do not waste memory on mods with no tracepoints	2014-05-30 21:52:11 -07:00
tsacct.c
uid16.c	groups: Consolidate the setgroups permission checks	2015-01-08 09:58:16 -08:00
up.c
user-return-notifier.c
user.c	userns: Add a knob to disable setgroups on a per user namespace basis	2015-01-08 09:58:16 -08:00
user_namespace.c	userns: Allow setting gid_maps without privilege when setgroups is disabled	2015-01-08 09:58:17 -08:00
utsname.c	proc: Split the namespace stuff out into linux/proc_ns.h	2013-05-01 17:29:39 -04:00
utsname_sysctl.c
wait.c
watchdog.c
workqueue.c	Revert "workqueue: make sure delayed work run in local cpu"	2016-03-03 15:06:24 -08:00
workqueue_internal.h	workqueue: include workqueue info when printing debug dump of a worker task	2013-04-30 17:04:02 -07:00