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Steven Rostedt (VMware) 657df1f079 tracing: Do not reference char * as a string in histograms 
commit 704adfb5a9978462cd861f170201ae2b5e3d3a80 upstream.

The histogram logic was allowing events with char * pointers to be used as
normal strings. But it was easy to crash the kernel with:

 # echo 'hist:keys=filename' > events/syscalls/sys_enter_openat/trigger

And open some files, and boom!

 BUG: unable to handle page fault for address: 00007f2ced0c3280
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 1173fa067 P4D 1173fa067 PUD 1171b6067 PMD 1171dd067 PTE 0
 Oops: 0000 [#1] PREEMPT SMP
 CPU: 6 PID: 1810 Comm: cat Not tainted 5.13.0-rc5-test+ #61
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01
v03.03 07/14/2016
 RIP: 0010:strlen+0x0/0x20
 Code: f6 82 80 2a 0b a9 20 74 11 0f b6 50 01 48 83 c0 01 f6 82 80 2a 0b
a9 20 75 ef c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <80> 3f 00 74
10 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 c3

 RSP: 0018:ffffbdbf81567b50 EFLAGS: 00010246
 RAX: 0000000000000003 RBX: ffff93815cdb3800 RCX: ffff9382401a22d0
 RDX: 0000000000000100 RSI: 0000000000000000 RDI: 00007f2ced0c3280
 RBP: 0000000000000100 R08: ffff9382409ff074 R09: ffffbdbf81567c98
 R10: ffff9382409ff074 R11: 0000000000000000 R12: ffff9382409ff074
 R13: 0000000000000001 R14: ffff93815a744f00 R15: 00007f2ced0c3280
 FS:  00007f2ced0f8580(0000) GS:ffff93825a800000(0000)
knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f2ced0c3280 CR3: 0000000107069005 CR4: 00000000001706e0
 Call Trace:
  event_hist_trigger+0x463/0x5f0
  ? find_held_lock+0x32/0x90
  ? sched_clock_cpu+0xe/0xd0
  ? lock_release+0x155/0x440
  ? kernel_init_free_pages+0x6d/0x90
  ? preempt_count_sub+0x9b/0xd0
  ? kernel_init_free_pages+0x6d/0x90
  ? get_page_from_freelist+0x12c4/0x1680
  ? __rb_reserve_next+0xe5/0x460
  ? ring_buffer_lock_reserve+0x12a/0x3f0
  event_triggers_call+0x52/0xe0
  ftrace_syscall_enter+0x264/0x2c0
  syscall_trace_enter.constprop.0+0x1ee/0x210
  do_syscall_64+0x1c/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Where it triggered a fault on strlen(key) where key was the filename.

The reason is that filename is a char * to user space, and the histogram
code just blindly dereferenced it, with obvious bad results.

I originally tried to use strncpy_from_user/kernel_nofault() but found
that there's other places that its dereferenced and not worth the effort.

Just do not allow "char *" to act like strings.

Link: https://lkml.kernel.org/r/20210715000206.025df9d2@rorschach.local.home

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Tom Zanussi <zanussi@kernel.org>
Fixes: 79e577cbce4c4 ("tracing: Support string type key properly")
Fixes: 5967bd5c4239 ("tracing: Let filter_assign_type() detect FILTER_PTR_STRING")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-20 16:21:11 +02:00
..
bpf
bpf: Check for integer overflow when using roundup_pow_of_two()
2021-02-23 13:59:16 +01:00
configs
config: android: enable CONFIG_SECCOMP
2016-10-11 15:06:32 -07:00
debug
kdb: Make memory allocations more robust
2021-03-03 17:44:31 +01:00
events
perf: Fix data race between pin_count increment/decrement
2021-06-16 11:36:35 +02:00
gcov
gcov: add support for GCC 10.1
2020-09-23 08:46:14 +02:00
irq
genirq: Disable interrupts for force threaded handlers
2021-03-24 10:59:26 +01:00
livepatch
livepatch/module: make TAINT_LIVEPATCH module-specific
2016-08-26 14:42:08 +02:00
locking
futex: Handle early deadlock return correctly
2021-03-30 14:41:42 +02:00
power
PM: hibernate: remove the bogus call to get_gendisk() in software_resume()
2020-10-29 09:05:43 +01:00
printk
printk: fix deadlock when kernel panic
2021-03-07 11:25:56 +01:00
rcu
rcuperf: Fix cleanup path for invalid perf_type strings
2019-05-31 06:48:30 -07:00
sched
sched/fair: handle case of task_h_load() returning 0
2020-07-22 09:10:54 +02:00
time
kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data()
2021-03-24 10:59:25 +01:00
trace
tracing: Do not reference char * as a string in histograms
2021-07-20 16:21:11 +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_watch.c
audit: CONFIG_CHANGE don't log internal bookkeeping as an event
2020-10-01 20:40:07 +02:00
audit.c
audit: fix a net reference leak in audit_list_rules_send()
2021-04-07 12:05:41 +02:00
audit.h
audit: fix a net reference leak in audit_list_rules_send()
2021-04-07 12:05:41 +02:00
auditfilter.c
audit: fix a net reference leak in audit_list_rules_send()
2021-04-07 12:05:41 +02:00
auditsc.c
audit: print empty EXECVE args
2019-11-28 18:28:55 +01:00
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: use atomic64_t for pids->limit
2019-12-21 10:42:02 +01:00
cgroup.c
cgroup1: don't allow '\n' in renaming
2021-06-16 11:36:34 +02:00
compat.c
…
configs.c
…
context_tracking.c
…
cpu_pm.c
kernel/cpu_pm: Fix uninitted local in cpu_pm
2020-06-20 10:24:21 +02:00
cpu.c
kernel/cpu: add arch override for clear_tasks_mm_cpumask() mm handling
2020-12-29 13:44:50 +01:00
cpuset.c
sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs
2017-10-12 11:51:25 +02:00
crash_dump.c
…
cred.c
memcg: account security cred as well to kmemcg
2020-01-12 11:24:13 +01:00
delayacct.c
…
dma.c
…
exec_domain.c
…
exit.c
futex: Mark the begin of futex exit explicitly
2021-02-03 23:19:49 +01:00
extable.c
kernel/extable.c: mark core_kernel_text notrace
2017-07-21 07:42:21 +02:00
fork.c
futex: Split futex_mm_release() for exit/exec
2021-02-03 23:19:49 +01:00
freezer.c
freezer, oom: check TIF_MEMDIE on the correct task
2016-07-28 16:07:41 -07:00
futex.c
mm, futex: fix shared futex pgoff on shmem huge page
2021-07-11 12:46:40 +02:00
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
…
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
kernel: kexec_file: fix error return code of kexec_calculate_store_digests()
2021-05-22 10:40:31 +02:00
kexec_internal.h
…
kexec.c
kexec: allow architectures to override boot mapping
2016-08-02 19:35:27 -04:00
kmod.c
usermodehelper: reset umask to default before executing user process
2020-10-14 09:48:14 +02:00
kprobes.c
kretprobe: Avoid re-registration of the same kretprobe earlier
2021-02-10 09:09:25 +01:00
ksysfs.c
kexec: add a kexec_crash_loaded() function
2016-08-02 19:35:30 -04:00
kthread.c
kthread: prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync()
2021-07-11 12:46:41 +02:00
latencytop.c
…
Makefile
elfcore: fix building with clang
2021-02-10 09:09:25 +01:00
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
…
module-internal.h
…
module.c
module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols
2021-03-03 17:44:44 +01:00
notifier.c
x86/mm: split vmalloc_sync_all()
2020-04-02 17:20:26 +02:00
nsproxy.c
…
padata.c
padata: purge get_cpu and reorder_via_wq from padata_do_serial
2020-05-27 16:41:53 +02:00
panic.c
panic: ensure preemption is disabled during panic()
2019-10-17 13:42:25 -07:00
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: make ptrace() fail if the tracee changed its pid unexpectedly
2021-05-26 11:29:06 +02:00
range.c
…
reboot.c
reboot: fix overflow parsing reboot cpu number
2020-11-18 18:26:32 +01:00
relay.c
kernel/relay.c: fix memleak on destroy relay channel
2020-08-26 10:29:03 +02:00
resource.c
resource: fix integer overflow at reallocation
2018-04-24 09:34:09 +02:00
seccomp.c
seccomp: Add missing return in non-void function
2021-03-03 17:44:43 +01:00
signal.c
signal: Extend exec_id to 64bits
2020-04-24 07:58:54 +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: avoid copying possible padding bytes in copy_to_user
2020-10-01 20:40:04 +02:00
sysctl_binary.c
kernel/sysctl_binary.c: use generic UUID library
2016-05-20 17:58:30 -07:00
sysctl.c
sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds
2020-07-09 09:35:55 +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 data-race
2020-01-12 11:24:12 +01:00
test_kprobes.c
…
torture.c
torture: Convert torture_shutdown() to hrtimer
2016-08-22 10:01:49 -07:00
tracepoint.c
tracepoint: Do not fail unregistering a probe due to memory failure
2021-03-03 17:44:38 +01:00
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
wq: handle VM suspension in stall detection
2021-06-16 11:36:33 +02:00