linux/kernel/trace
Steven Rostedt 2cf30dc180 tracing: Have filter check for balanced ops
When the following filter is used it causes a warning to trigger:

 # cd /sys/kernel/debug/tracing
 # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
 # cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: No error

 ------------[ cut here ]------------
 WARNING: CPU: 2 PID: 1223 at kernel/trace/trace_events_filter.c:1640 replace_preds+0x3c5/0x990()
 Modules linked in: bnep lockd grace bluetooth  ...
 CPU: 3 PID: 1223 Comm: bash Tainted: G        W       4.1.0-rc3-test+ #450
 Hardware name: Hewlett-Packard HP Compaq Pro 6300 SFF/339A, BIOS K01 v02.05 05/07/2012
  0000000000000668 ffff8800c106bc98 ffffffff816ed4f9 ffff88011ead0cf0
  0000000000000000 ffff8800c106bcd8 ffffffff8107fb07 ffffffff8136b46c
  ffff8800c7d81d48 ffff8800d4c2bc00 ffff8800d4d4f920 00000000ffffffea
 Call Trace:
  [<ffffffff816ed4f9>] dump_stack+0x4c/0x6e
  [<ffffffff8107fb07>] warn_slowpath_common+0x97/0xe0
  [<ffffffff8136b46c>] ? _kstrtoull+0x2c/0x80
  [<ffffffff8107fb6a>] warn_slowpath_null+0x1a/0x20
  [<ffffffff81159065>] replace_preds+0x3c5/0x990
  [<ffffffff811596b2>] create_filter+0x82/0xb0
  [<ffffffff81159944>] apply_event_filter+0xd4/0x180
  [<ffffffff81152bbf>] event_filter_write+0x8f/0x120
  [<ffffffff811db2a8>] __vfs_write+0x28/0xe0
  [<ffffffff811dda43>] ? __sb_start_write+0x53/0xf0
  [<ffffffff812e51e0>] ? security_file_permission+0x30/0xc0
  [<ffffffff811dc408>] vfs_write+0xb8/0x1b0
  [<ffffffff811dc72f>] SyS_write+0x4f/0xb0
  [<ffffffff816f5217>] system_call_fastpath+0x12/0x6a
 ---[ end trace e11028bd95818dcd ]---

Worse yet, reading the error message (the filter again) it says that
there was no error, when there clearly was. The issue is that the
code that checks the input does not check for balanced ops. That is,
having an op between a closed parenthesis and the next token.

This would only cause a warning, and fail out before doing any real
harm, but it should still not caues a warning, and the error reported
should work:

 # cd /sys/kernel/debug/tracing
 # echo "((dev==1)blocks==2)" > events/ext4/ext4_truncate_exit/filter
-bash: echo: write error: Invalid argument
 # cat events/ext4/ext4_truncate_exit/filter
((dev==1)blocks==2)
^
parse_error: Meaningless filter expression

And give no kernel warning.

Link: http://lkml.kernel.org/r/20150615175025.7e809215@gandalf.local.home

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: stable@vger.kernel.org # 2.6.31+
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2015-06-17 07:13:30 -04:00
..
blktrace.c Merge branch 'for-3.19/core' of git://git.kernel.dk/linux-block 2014-12-13 14:14:23 -08:00
bpf_trace.c tracing: Allow BPF programs to call bpf_trace_printk() 2015-04-02 13:25:50 +02:00
ftrace.c Some clean ups and small fixes, but the biggest change is the addition 2015-04-14 10:49:03 -07:00
Kconfig Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-14 14:37:47 -07:00
Makefile bpf: Fix the build on BPF_SYSCALL=y && !CONFIG_TRACING kernels, make it more configurable 2015-04-02 16:28:06 +02:00
power-traces.c PM / sleep: export suspend_resume trace event 2015-01-30 02:10:41 +01:00
ring_buffer_benchmark.c ring-buffer-benchmark: Fix the wrong sched_priority of producer 2015-06-11 09:27:58 -04:00
ring_buffer.c ring-buffer: Remove duplicate use of '&' in recursive code 2015-03-30 13:36:31 -04:00
rpm-traces.c PM / Runtime: Introduce trace points for tracing rpm_* functions 2011-09-27 22:53:27 +02:00
trace_benchmark.c tracing: Only calculate stats of tracepoint benchmarks for 2^32 times 2014-06-06 00:41:38 -04:00
trace_benchmark.h tracing: Add tracepoint benchmark tracepoint 2014-05-29 22:49:54 -04:00
trace_branch.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_clock.c tracing: Fix wraparound problems in "uptime" trace clock 2014-07-21 09:56:12 -04:00
trace_entries.h tracing: %pF is only for function pointers 2015-03-25 08:57:22 -04:00
trace_event_perf.c perf: Avoid horrible stack usage 2015-01-14 15:11:45 +01:00
trace_events_filter_test.h tracing/filter: Add startup tests for events filter 2011-08-19 14:35:59 -04:00
trace_events_filter.c tracing: Have filter check for balanced ops 2015-06-17 07:13:30 -04:00
trace_events_trigger.c trace: Replace single-character seq_puts with seq_putc 2014-11-14 07:55:55 -05:00
trace_events.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-04-26 17:22:07 -07:00
trace_export.c tracing: remove ftrace:function TRACE_EVENT_FL_USE_CALL_FILTER flag 2015-03-25 08:57:23 -04:00
trace_functions_graph.c This adds three fixes for the tracing code. 2015-04-22 11:27:36 -07:00
trace_functions.c tracing/trivial: Fix typos and make an int into a bool 2014-11-20 10:05:36 -05:00
trace_irqsoff.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_kdb.c KGDB/KDB fixes and cleanups 2015-01-09 20:51:10 -08:00
trace_kprobe.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-14 14:37:47 -07:00
trace_mmiotrace.c tracing: Do not check return values of trace_seq_p*() for mmio tracer 2014-11-19 15:25:44 -05:00
trace_nop.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_output.c tracing: Make ftrace_print_array_seq compute buf_len 2015-05-06 23:03:23 -04:00
trace_output.h tracing: Add trace_seq_has_overflowed() and trace_handle_return() 2014-11-19 15:25:39 -05:00
trace_printk.c tracing: Use IS_ERR() check for return value of tracing_init_dentry() 2015-01-22 11:19:49 -05:00
trace_probe.c trace: Don't use __weak in header files 2015-03-25 08:57:23 -04:00
trace_probe.h Some clean ups and small fixes, but the biggest change is the addition 2015-04-14 10:49:03 -07:00
trace_sched_switch.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_sched_wakeup.c tracing: Remove unneeded includes of debugfs.h and fs.h 2015-01-22 11:19:48 -05:00
trace_selftest_dynamic.c ftrace: Add self-tests for multiple function trace users 2011-05-18 19:24:51 -04:00
trace_selftest.c Seems that Peter Zijlstra added a new check that is making old 2014-10-12 07:28:55 -04:00
trace_seq.c tracing: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
trace_stack.c tracing: remove use of seq_printf return value 2015-04-15 16:35:25 -07:00
trace_stat.c tracing: Convert the tracing facility over to use tracefs 2015-02-03 12:48:41 -05:00
trace_stat.h
trace_syscalls.c perf: Avoid horrible stack usage 2015-01-14 15:11:45 +01:00
trace_uprobe.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-04-26 17:22:07 -07:00
trace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-04-26 17:22:07 -07:00
trace.h Some clean ups and small fixes, but the biggest change is the addition 2015-04-14 10:49:03 -07:00