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Eiichi Tsukata fc19ad387e tracing/snapshot: Resize spare buffer if size changed 
commit 46cc0b44428d0f0e81f11ea98217fc0edfbeab07 upstream.

Current snapshot implementation swaps two ring_buffers even though their
sizes are different from each other, that can cause an inconsistency
between the contents of buffer_size_kb file and the current buffer size.

For example:

  # cat buffer_size_kb
  7 (expanded: 1408)
  # echo 1 > events/enable
  # grep bytes per_cpu/cpu0/stats
  bytes: 1441020
  # echo 1 > snapshot             // current:1408, spare:1408
  # echo 123 > buffer_size_kb     // current:123,  spare:1408
  # echo 1 > snapshot             // current:1408, spare:123
  # grep bytes per_cpu/cpu0/stats
  bytes: 1443700
  # cat buffer_size_kb
  123                             // != current:1408

And also, a similar per-cpu case hits the following WARNING:

Reproducer:

  # echo 1 > per_cpu/cpu0/snapshot
  # echo 123 > buffer_size_kb
  # echo 1 > per_cpu/cpu0/snapshot

WARNING:

  WARNING: CPU: 0 PID: 1946 at kernel/trace/trace.c:1607 update_max_tr_single.part.0+0x2b8/0x380
  Modules linked in:
  CPU: 0 PID: 1946 Comm: bash Not tainted 5.2.0-rc6 
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30 04/01/2014
  RIP: 0010:update_max_tr_single.part.0+0x2b8/0x380
  Code: ff e8 dc da f9 ff 0f 0b e9 88 fe ff ff e8 d0 da f9 ff 44 89 ee bf f5 ff ff ff e8 33 dc f9 ff 41 83 fd f5 74 96 e8 b8 da f9 ff <0f> 0b eb 8d e8 af da f9 ff 0f 0b e9 bf fd ff ff e8 a3 da f9 ff 48
  RSP: 0018:ffff888063e4fca0 EFLAGS: 00010093
  RAX: ffff888066214380 RBX: ffffffff99850fe0 RCX: ffffffff964298a8
  RDX: 0000000000000000 RSI: 00000000fffffff5 RDI: 0000000000000005
  RBP: 1ffff1100c7c9f96 R08: ffff888066214380 R09: ffffed100c7c9f9b
  R10: ffffed100c7c9f9a R11: 0000000000000003 R12: 0000000000000000
  R13: 00000000ffffffea R14: ffff888066214380 R15: ffffffff99851060
  FS:  00007f9f8173c700(0000) GS:ffff88806d000000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000714dc0 CR3: 0000000066fa6000 CR4: 00000000000006f0
  Call Trace:
   ? trace_array_printk_buf+0x140/0x140
   ? __mutex_lock_slowpath+0x10/0x10
   tracing_snapshot_write+0x4c8/0x7f0
   ? trace_printk_init_buffers+0x60/0x60
   ? selinux_file_permission+0x3b/0x540
   ? tracer_preempt_off+0x38/0x506
   ? trace_printk_init_buffers+0x60/0x60
   __vfs_write+0x81/0x100
   vfs_write+0x1e1/0x560
   ksys_write+0x126/0x250
   ? __ia32_sys_read+0xb0/0xb0
   ? do_syscall_64+0x1f/0x390
   do_syscall_64+0xc1/0x390
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

This patch adds resize_buffer_duplicate_size() to check if there is a
difference between current/spare buffer sizes and resize a spare buffer
if necessary.

Link: http://lkml.kernel.org/r/20190625012910.13109-1-devel@etsukata.com

Cc: stable@vger.kernel.org
Fixes: ad909e21bbe69 ("tracing: Add internal tracing_snapshot() functions")
Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-08-04 09:33:26 +02:00
..
bpf
bpf: silence warning messages in core
2019-08-04 09:33:19 +02:00
configs
config: android: enable CONFIG_SECCOMP
2016-10-11 15:06:32 -07:00
debug
kdb: use memmove instead of overlapping memcpy
2018-12-08 13:05:05 +01:00
events
perf/core: Fix perf_sample_regs_user() mm check
2019-07-21 09:06:05 +02:00
gcov
gcov: support GCC 7.1
2017-09-02 07:07:53 +02:00
irq
genirq: Prevent use-after-free and work list corruption
2019-05-10 17:52:10 +02:00
livepatch
livepatch/module: make TAINT_LIVEPATCH module-specific
2016-08-26 14:42:08 +02:00
locking
locking/lockdep: Fix merging of hlocks with non-zero references
2019-08-04 09:33:17 +02:00
power
x86/power: Fix 'nosmt' vs hibernation triple fault during resume
2019-06-11 12:22:48 +02:00
printk
printk: Fix panic caused by passing log_buf_len to command line
2018-11-13 11:17:01 -08:00
rcu
rcuperf: Fix cleanup path for invalid perf_type strings
2019-05-31 06:48:30 -07:00
sched
sched/core: Handle overflow in cpu_shares_write_u64
2019-05-31 06:48:22 -07:00
time
timer_list: Guard procfs specific code
2019-08-04 09:33:21 +02:00
trace
tracing/snapshot: Resize spare buffer if size changed
2019-08-04 09:33:26 +02:00
.gitignore
…
acct.c
kernel/acct.c: fix the acct->needcheck check in check_free_space()
2018-01-10 09:29:51 +01:00
async.c
kernel/async.c: revert "async: simplify lowest_in_progress()"
2018-02-17 13:21:18 +01:00
audit_fsnotify.c
…
audit_tree.c
audit: cleanup prune_tree_thread
2016-04-04 09:46:47 -04:00
audit_watch.c
audit: fix use-after-free in audit_add_watch
2018-09-26 08:36:37 +02:00
audit.c
audit: return on memory error to avoid null pointer dereference
2018-05-30 07:50:49 +02:00
audit.h
Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit
2016-07-29 17:54:17 -07:00
auditfilter.c
audit: fix a memory leak bug
2019-05-31 06:48:20 -07:00
auditsc.c
audit: allow not equal op for audit by executable
2018-08-03 07:55:25 +02:00
backtracetest.c
…
bounds.c
kbuild: fix kernel/bounds.c 'W=1' warning
2018-11-13 11:16:57 -08:00
capability.c
ptrace: Capture the ptracer's creds not PT_PTRACE_CAP
2017-01-06 10:40:13 +01:00
cgroup_freezer.c
…
cgroup_pids.c
cgroup/pids: remove spurious suspicious RCU usage warning
2017-03-26 13:05:58 +02:00
cgroup.c
cgroup: Fix deadlock in cpu hotplug path
2018-10-13 09:18:56 +02:00
compat.c
…
configs.c
…
context_tracking.c
…
cpu_pm.c
…
cpu.c
cpu/speculation: Warn on unsupported mitigations= parameter
2019-07-10 09:55:39 +02:00
cpuset.c
sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
2017-10-12 11:51:25 +02:00
crash_dump.c
…
cred.c
ptrace: restore smp_rmb() in __ptrace_may_access()
2019-06-22 08:17:18 +02:00
delayacct.c
…
dma.c
…
elfcore.c
…
exec_domain.c
…
exit.c
kernel/exit.c: release ptraced tasks before zap_pid_ns_processes
2019-02-06 17:33:29 +01:00
extable.c
kernel/extable.c: mark core_kernel_text notrace
2017-07-21 07:42:21 +02:00
fork.c
fork: record start_time late
2019-01-13 10:03:51 +01:00
freezer.c
freezer, oom: check TIF_MEMDIE on the correct task
2016-07-28 16:07:41 -07:00
futex_compat.c
…
futex.c
futex: Ensure that futex address is aligned in handle_futex_death()
2019-03-27 14:13:03 +09:00
groups.c
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
hung_task.c
kernel: hung_task.c: disable on suspend
2019-04-20 09:07:52 +02:00
irq_work.c
…
jump_label.c
jump_label: Invoke jump_label_test() via early_initcall()
2017-12-14 09:28:24 +01:00
kallsyms.c
kallsyms: add support for relative offsets in kallsyms address table
2016-03-15 16:55:16 -07:00
kcmp.c
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks
…
Kconfig.preempt
…
kcov.c
kcov: ensure irq code sees a valid area
2018-08-03 07:55:12 +02:00
kexec_core.c
objtool, x86: Add several functions and files to the objtool whitelist
2018-06-05 10:28:57 +02:00
kexec_file.c
kexec: fix double-free when failing to relocate the purgatory
2016-09-01 17:52:01 -07:00
kexec_internal.h
…
kexec.c
kexec: allow architectures to override boot mapping
2016-08-02 19:35:27 -04:00
kmod.c
…
kprobes.c
kprobes: Fix error check when reusing optimized probes
2019-04-27 09:34:45 +02:00
ksysfs.c
kexec: add a kexec_crash_loaded() function
2016-08-02 19:35:30 -04:00
kthread.c
kthread, tracing: Don't expose half-written comm when creating kthreads
2018-08-03 07:55:12 +02:00
latencytop.c
…
Makefile
x86/uaccess, kcov: Disable stack protector
2019-06-22 08:17:19 +02:00
membarrier.c
Fix: Disable sys_membarrier when nohz_full is enabled
2017-03-12 06:41:45 +01:00
memremap.c
mm, devm_memremap_pages: kill mapping "System RAM" support
2019-01-13 10:03:51 +01:00
module_signing.c
KEYS: Move the point of trust determination to __key_link()
2016-04-11 22:43:43 +01:00
module-internal.h
…
module.c
module: exclude SHN_UNDEF symbols from kallsyms api
2018-10-03 17:01:48 -07:00
notifier.c
…
nsproxy.c
…
padata.c
padata: free correct variable
2017-05-20 14:28:40 +02:00
panic.c
panic: avoid deadlocks in re-entrant console drivers
2018-12-29 13:40:16 +01:00
params.c
…
pid_namespace.c
signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig
2019-08-04 09:33:16 +02:00
pid.c
pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid()
2018-04-13 19:47:53 +02:00
profile.c
profile: Convert to hotplug state machine
2016-07-15 10:41:42 +02:00
ptrace.c
ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME
2019-07-10 09:55:45 +02:00
range.c
…
reboot.c
…
relay.c
kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE
2018-05-30 07:50:29 +02:00
resource.c
resource: fix integer overflow at reallocation
2018-04-24 09:34:09 +02:00
seccomp.c
seccomp: Move speculation migitation control to arch code
2018-05-22 16:58:02 +02:00
signal.c
kernel/signal.c: trace_signal_deliver when signal_group_exit
2019-06-11 12:22:43 +02:00
smp.c
cpu/hotplug: Fix SMT supported evaluation
2018-08-15 18:14:53 +02:00
smpboot.c
kthread/smpboot: do not park in kthread_create_on_cpu()
2016-10-11 15:06:33 -07:00
smpboot.h
…
softirq.c
Mark HI and TASKLET softirq synchronous
2018-08-15 18:14:42 +02:00
stacktrace.c
stacktrace, lockdep: Fix address, newline ugliness
2017-02-14 15:25:42 -08:00
stop_machine.c
stop_machine: Use raw spinlocks
2018-08-03 07:55:24 +02:00
sys_ni.c
x86/pkeys: Fix pkeys build breakage for some non-x86 arches
2016-09-13 14:41:36 +02:00
sys.c
kernel/sys.c: prctl: fix false positive in validate_prctl_map()
2019-06-22 08:17:13 +02:00
sysctl_binary.c
kernel/sysctl_binary.c: use generic UUID library
2016-05-20 17:58:30 -07:00
sysctl.c
sysctl: return -EINVAL if val violates minmax
2019-06-22 08:17:11 +02:00
task_work.c
task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works
2016-08-02 19:35:02 -04:00
taskstats.c
taskstats: fix the length of cgroupstats_cmd_get_policy
2016-11-03 16:55:58 -04:00
test_kprobes.c
…
torture.c
torture: Convert torture_shutdown() to hrtimer
2016-08-22 10:01:49 -07:00
tracepoint.c
tracepoint: Do not warn on ENOMEM
2018-05-09 09:50:20 +02:00
tsacct.c
…
ucount.c
kernel/ucount.c: mark user_header with kmemleak_ignore()
2017-06-17 06:41:51 +02:00
uid16.c
kernel: make groups_sort calling a responsibility group_info allocators
2018-01-10 09:29:52 +01:00
up.c
smp: Add function to execute a function synchronously on a CPU
2016-09-05 13:52:39 +02:00
user_namespace.c
userns: move user access out of the mutex
2018-09-09 20:01:24 +02:00
user-return-notifier.c
…
user.c
…
utsname_sysctl.c
sys: don't hold uts_sem while accessing userspace memory
2018-09-09 20:01:24 +02:00
utsname.c
Merge branch 'nsfs-ioctls' into HEAD
2016-09-22 20:00:36 -05:00
watchdog_hld.c
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
watchdog.c
kernel/watchdog: prevent false hardlockup on overloaded system
2017-06-17 06:41:57 +02:00
workqueue_internal.h
workqueue: Fix NULL pointer dereference
2017-11-15 15:53:17 +01:00
workqueue.c
workqueue: use put_device() instead of kfree()
2018-05-30 07:50:36 +02:00