linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	stable@vger.kernel.org, Tom Zanussi <zanussi@kernel.org>
Subject: [for-linus][PATCH 2/7] tracing: Synthetic event field_pos is an index not a boolean
Date: Fri, 23 Jul 2021 08:54:56 -0400	[thread overview]
Message-ID: <20210723125633.655004181@goodmis.org> (raw)
In-Reply-To: <20210723125454.570472450@goodmis.org>

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Performing the following:

 ># echo 'wakeup_lat s32 pid; u64 delta; char wake_comm[]' > synthetic_events
 ># echo 'hist:keys=pid:__arg__1=common_timestamp.usecs' > events/sched/sched_waking/trigger
 ># echo 'hist:keys=next_pid:pid=next_pid,delta=common_timestamp.usecs-$__arg__1:onmatch(sched.sched_waking).trace(wakeup_lat,$pid,$delta,prev_comm)'\
      > events/sched/sched_switch/trigger
 ># echo 1 > events/synthetic/enable

Crashed the kernel:

 BUG: kernel NULL pointer dereference, address: 000000000000001b
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP
 CPU: 7 PID: 0 Comm: swapper/7 Not tainted 5.13.0-rc5-test+ #104
 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 2b 0b bc 20 74 11 0f b6 50 01 48 83 c0 01 f6 82 80 2b 0b bc
  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 9 f8 c3 31
 RSP: 0018:ffffaa75000d79d0 EFLAGS: 00010046
 RAX: 0000000000000002 RBX: ffff9cdb55575270 RCX: 0000000000000000
 RDX: ffff9cdb58c7a320 RSI: ffffaa75000d7b40 RDI: 000000000000001b
 RBP: ffffaa75000d7b40 R08: ffff9cdb40a4f010 R09: ffffaa75000d7ab8
 R10: ffff9cdb4398c700 R11: 0000000000000008 R12: ffff9cdb58c7a320
 R13: ffff9cdb55575270 R14: ffff9cdb58c7a000 R15: 0000000000000018
 FS:  0000000000000000(0000) GS:ffff9cdb5aa00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 000000000000001b CR3: 00000000c0612006 CR4: 00000000001706e0
 Call Trace:
  trace_event_raw_event_synth+0x90/0x1d0
  action_trace+0x5b/0x70
  event_hist_trigger+0x4bd/0x4e0
  ? cpumask_next_and+0x20/0x30
  ? update_sd_lb_stats.constprop.0+0xf6/0x840
  ? __lock_acquire.constprop.0+0x125/0x550
  ? find_held_lock+0x32/0x90
  ? sched_clock_cpu+0xe/0xd0
  ? lock_release+0x155/0x440
  ? update_load_avg+0x8c/0x6f0
  ? enqueue_entity+0x18a/0x920
  ? __rb_reserve_next+0xe5/0x460
  ? ring_buffer_lock_reserve+0x12a/0x3f0
  event_triggers_call+0x52/0xe0
  trace_event_buffer_commit+0x1ae/0x240
  trace_event_raw_event_sched_switch+0x114/0x170
  __traceiter_sched_switch+0x39/0x50
  __schedule+0x431/0xb00
  schedule_idle+0x28/0x40
  do_idle+0x198/0x2e0
  cpu_startup_entry+0x19/0x20
  secondary_startup_64_no_verify+0xc2/0xcb

The reason is that the dynamic events array keeps track of the field
position of the fields array, via the field_pos variable in the
synth_field structure. Unfortunately, that field is a boolean for some
reason, which means any field_pos greater than 1 will be a bug (in this
case it was 2).

Link: https://lkml.kernel.org/r/20210721191008.638bce34@oasis.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Fixes: bd82631d7ccdc ("tracing: Add support for dynamic strings to synthetic events")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_synth.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_synth.h b/kernel/trace/trace_synth.h
index 6e146b959dcd..4007fe95cf42 100644
--- a/kernel/trace/trace_synth.h
+++ b/kernel/trace/trace_synth.h
@@ -14,10 +14,10 @@ struct synth_field {
 	char *name;
 	size_t size;
 	unsigned int offset;
+	unsigned int field_pos;
 	bool is_signed;
 	bool is_string;
 	bool is_dynamic;
-	bool field_pos;
 };
 
 struct synth_event {
-- 
2.30.2

  parent reply	other threads:[~2021-07-23 12:56 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23 12:54 [for-linus][PATCH 0/7] tracing: Fixes for 5.14-rc2 Steven Rostedt
2021-07-23 12:54 ` [for-linus][PATCH 1/7] tracing: Fix bug in rb_per_cpu_empty() that might cause deadloop Steven Rostedt
2021-07-23 12:54 ` Steven Rostedt [this message]
2021-07-23 12:54 ` [for-linus][PATCH 3/7] tracing/histogram: Rename "cpu" to "common_cpu" Steven Rostedt
2021-07-23 12:54 ` [for-linus][PATCH 4/7] tracing: Clean up alloc_synth_event() Steven Rostedt
2021-07-23 12:54 ` [for-linus][PATCH 5/7] ftrace: Avoid synchronize_rcu_tasks_rude() call when not necessary Steven Rostedt
2021-07-23 12:55 ` [for-linus][PATCH 6/7] ftrace: Remove redundant initialization of variable ret Steven Rostedt
2021-07-23 12:55 ` [for-linus][PATCH 7/7] tracepoints: Update static_call before tp_funcs when adding a tracepoint Steven Rostedt

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210723125633.655004181@goodmis.org \
    --to=rostedt@goodmis.org \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=mingo@kernel.org \
    --cc=namhyung@kernel.org \
    --cc=stable@vger.kernel.org \
    --cc=zanussi@kernel.org \
    --subject='Re: [for-linus][PATCH 2/7] tracing: Synthetic event field_pos is an index not a boolean' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).