linux/kernel
Elena Reshetova ca3bb3d027 perf/ring_buffer: Convert ring_buffer.aux_refcount to refcount_t
atomic_t variables are currently used to implement reference
counters with the following properties:

 - counter is initialized to 1 using atomic_set()
 - a resource is freed upon counter reaching zero
 - once counter reaches zero, its further
   increments aren't allowed
 - counter schema uses basic atomic operations
   (set, inc, inc_not_zero, dec_and_test, etc.)

Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.

The variable ring_buffer.aux_refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.

** Important note for maintainers:

Some functions from refcount_t API defined in lib/refcount.c
have different memory ordering guarantees than their atomic
counterparts. Please check Documentation/core-api/refcount-vs-atomic.rst
for more information.

Normally the differences should not matter since refcount_t provides
enough guarantees to satisfy the refcounting use cases, but in
some rare cases it might matter.
Please double check that you don't have some undocumented
memory guarantees for this variable usage.

For the ring_buffer.aux_refcount it might make a difference
in following places:

 - perf_aux_output_begin(): increment in refcount_inc_not_zero() only
   guarantees control dependency on success vs. fully ordered
   atomic counterpart
 - rb_free_aux(): decrement in refcount_dec_and_test() only
   provides RELEASE ordering and ACQUIRE ordering + control dependency
   on success vs. fully ordered atomic counterpart

Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: acme@kernel.org
Cc: namhyung@kernel.org
Link: https://lkml.kernel.org/r/1548678448-24458-4-git-send-email-elena.reshetova@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:46:17 +01:00
..
bpf Merge branch 'perf/urgent' into perf/core, to pick up fixes 2019-02-04 08:45:42 +01:00
cgroup Merge branch 'for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2018-12-29 10:57:20 -08:00
configs kvm_config: add CONFIG_VIRTIO_MENU 2018-10-24 20:55:56 -04:00
debug kdb: use bool for binary state indicators 2018-12-30 08:31:52 +00:00
dma swiotlb: clear io_tlb_start and io_tlb_end in swiotlb_exit 2019-01-16 09:59:17 -05:00
events perf/ring_buffer: Convert ring_buffer.aux_refcount to refcount_t 2019-02-04 08:46:17 +01:00
gcov
irq genirq/irqdesc: Fix double increment in alloc_descs() 2019-01-18 00:43:09 +01:00
livepatch livepatch: Replace synchronize_sched() with synchronize_rcu() 2018-12-01 12:38:50 -08:00
locking locking/rwsem: Fix (possible) missed wakeup 2019-01-21 11:15:39 +01:00
power mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
printk Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
rcu rcutorture: Don't do busted forward-progress testing 2018-12-01 12:45:42 -08:00
sched Merge branch 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-02-03 09:02:03 -08:00
time posix-cpu-timers: Unbreak timer rearming 2019-01-15 16:34:37 +01:00
trace perf: Make perf_event_output() propagate the output() return 2019-01-21 17:00:57 -03:00
.gitignore
acct.c
async.c
audit_fsnotify.c audit: minimize our use of audit_log_format() 2018-11-26 18:40:00 -05:00
audit_tree.c audit: minimize our use of audit_log_format() 2018-11-26 18:40:00 -05:00
audit_watch.c audit: minimize our use of audit_log_format() 2018-11-26 18:40:00 -05:00
audit.c audit: remove duplicated include from audit.c 2018-12-14 12:09:30 -05:00
audit.h audit: use current whenever possible 2018-11-26 18:41:21 -05:00
auditfilter.c
auditsc.c audit: use current whenever possible 2018-11-26 18:41:21 -05:00
backtracetest.c
bounds.c kbuild: fix kernel/bounds.c 'W=1' warning 2018-10-31 08:54:14 -07:00
capability.c
compat.c make 'user_access_begin()' do 'access_ok()' 2019-01-04 12:56:09 -08:00
configs.c
context_tracking.c
cpu_pm.c
cpu.c cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM 2019-01-30 19:27:00 +01:00
crash_core.c kernel/crash_core.c: print timestamp using time64_t 2018-08-22 10:52:47 -07:00
crash_dump.c
cred.c cred: export get_task_cred(). 2018-12-19 13:52:44 -05:00
delayacct.c delayacct: track delays from thrashing cache pages 2018-10-26 16:26:32 -07:00
dma.c
elfcore.c
exec_domain.c
exit.c kernel/exit.c: release ptraced tasks before zap_pid_ns_processes 2019-02-01 15:46:23 -08:00
extable.c
fail_function.c kernel/fail_function.c: remove meaningless null pointer check before debugfs_remove_recursive 2018-10-31 08:54:12 -07:00
fork.c Merge branch 'akpm' (patches from Andrew) 2019-01-08 18:58:29 -08:00
freezer.c PM / reboot: Eliminate race between reboot and suspend 2018-08-06 12:35:20 +02:00
futex.c futex: Fix (possible) missed wakeup 2019-01-21 11:15:38 +01:00
groups.c
hung_task.c kernel/hung_task.c: break RCU locks based on jiffies 2019-01-04 13:13:45 -08:00
iomem.c
irq_work.c
jump_label.c jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
kallsyms.c bpf: Add module name [bpf] to ksymbols for bpf programs 2019-01-21 17:38:56 -03:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt kconfig: warn no new line at end of file 2018-12-15 17:44:35 +09:00
kcov.c kernel/kcov.c: mark write_comp_data() as notrace 2019-01-04 13:13:47 -08:00
kexec_core.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
kexec_file.c kexec_file: kexec_walk_memblock() only walks a dedicated region at kdump 2018-12-06 14:38:50 +00:00
kexec_internal.h
kexec.c kexec: add call to LSM hook in original kexec_load syscall 2018-07-16 12:31:57 -07:00
kmod.c
kprobes.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-12-26 14:45:18 -08:00
ksysfs.c
kthread.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-08-13 11:25:07 -07:00
latencytop.c
Makefile kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
memremap.c mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm 2018-12-28 12:11:52 -08:00
module_signing.c modsign: use all trusted keys to verify module signature 2018-11-07 14:41:41 +01:00
module-internal.h modsign: log module name in the event of an error 2018-07-02 11:36:17 +02:00
module.c jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
notifier.c
nsproxy.c
padata.c padata: clean an indentation issue, remove extraneous space 2018-11-16 14:11:04 +08:00
panic.c kernel/sysctl: add panic_print into sysctl 2019-01-04 13:13:47 -08:00
params.c
pid_namespace.c signal: Use group_send_sig_info to kill all processes in a pid namespace 2018-09-16 16:08:25 +02:00
pid.c Fix failure path in alloc_pid() 2018-12-28 12:42:30 -08:00
profile.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
ptrace.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
range.c
reboot.c kernel/reboot.c: export pm_power_off_prepare 2018-09-11 16:13:24 +01:00
relay.c
resource.c kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable 2018-12-28 12:11:49 -08:00
rseq.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
seccomp.c seccomp: fix UAF in user-trap code 2019-01-15 09:43:12 -08:00
signal.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
smp.c cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM 2019-01-30 19:27:00 +01:00
smpboot.c smpboot: Remove cpumask from the API 2018-07-03 09:20:44 +02:00
smpboot.h
softirq.c Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-25 11:43:47 -07:00
stackleak.c stackleak: Mark stackleak_track_stack() as notrace 2018-12-05 19:31:44 -08:00
stacktrace.c
stop_machine.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-08-13 11:25:07 -07:00
sys_ni.c y2038: socket: Add compat_sys_recvmmsg_time64 2018-12-18 16:13:04 +01:00
sys.c kernel/sys.c: Clarify that UNAME26 does not generate unique versions anymore 2019-01-14 10:38:03 +12:00
sysctl_binary.c kernel/sysctl: add panic_print into sysctl 2019-01-04 13:13:47 -08:00
sysctl.c kernel/sysctl: add panic_print into sysctl 2019-01-04 13:13:47 -08:00
task_work.c
taskstats.c
test_kprobes.c
torture.c torture: Remove unnecessary "ret" variables 2018-12-01 12:45:35 -08:00
tracepoint.c tracing: Replace synchronize_sched() and call_rcu_sched() 2018-11-27 09:21:41 -08:00
tsacct.c
ucount.c
uid16.c
uid16.h
umh.c umh: add exit routine for UMH process 2019-01-11 18:05:40 -08:00
up.c smp,cpumask: introduce on_each_cpu_cond_mask 2018-10-09 16:51:11 +02:00
user_namespace.c userns: also map extents in the reverse map to kernel IDs 2018-11-07 23:51:16 -06:00
user-return-notifier.c
user.c userns: use irqsave variant of refcount_dec_and_lock() 2018-08-22 10:52:47 -07:00
utsname_sysctl.c sys: don't hold uts_sem while accessing userspace memory 2018-08-11 02:05:53 -05:00
utsname.c
watchdog_hld.c watchdog: Mark watchdog touch functions as notrace 2018-08-30 12:56:40 +02:00
watchdog.c watchdog: Mark watchdog touch functions as notrace 2018-08-30 12:56:40 +02:00
workqueue_internal.h psi: fix aggregation idle shut-off 2019-02-01 15:46:23 -08:00
workqueue.c psi: fix aggregation idle shut-off 2019-02-01 15:46:23 -08:00