lkml.org 
[lkml]   [2020]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 5.4 19/58] tracing: Fix number printing bug in print_synth_event()
Date
From: Tom Zanussi <zanussi@kernel.org>

[ Upstream commit 784bd0847eda032ed2f3522f87250655a18c0190 ]

Fix a varargs-related bug in print_synth_event() which resulted in
strange output and oopses on 32-bit x86 systems. The problem is that
trace_seq_printf() expects the varargs to match the format string, but
print_synth_event() was always passing u64 values regardless. This
results in unspecified behavior when unpacking with va_arg() in
trace_seq_printf().

Add a function that takes the size into account when calling
trace_seq_printf().

Before:

modprobe-1731 [003] .... 919.039758: gen_synth_test: next_pid_field=777(null)next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=3(null)my_string_field=thneed my_int_field=598(null)

After:

insmod-1136 [001] .... 36.634590: gen_synth_test: next_pid_field=777 next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=1 my_string_field=thneed my_int_field=598

Link: http://lkml.kernel.org/r/a9b59eb515dbbd7d4abe53b347dccf7a8e285657.1581720155.git.zanussi@kernel.org

Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/trace/trace_events_hist.c | 32 +++++++++++++++++++++++++++++---
1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index a31be3fce3e8e..6495800fb92a1 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -811,6 +811,29 @@ static const char *synth_field_fmt(char *type)
return fmt;
}

+static void print_synth_event_num_val(struct trace_seq *s,
+ char *print_fmt, char *name,
+ int size, u64 val, char *space)
+{
+ switch (size) {
+ case 1:
+ trace_seq_printf(s, print_fmt, name, (u8)val, space);
+ break;
+
+ case 2:
+ trace_seq_printf(s, print_fmt, name, (u16)val, space);
+ break;
+
+ case 4:
+ trace_seq_printf(s, print_fmt, name, (u32)val, space);
+ break;
+
+ default:
+ trace_seq_printf(s, print_fmt, name, val, space);
+ break;
+ }
+}
+
static enum print_line_t print_synth_event(struct trace_iterator *iter,
int flags,
struct trace_event *event)
@@ -849,10 +872,13 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
} else {
struct trace_print_flags __flags[] = {
__def_gfpflag_names, {-1, NULL} };
+ char *space = (i == se->n_fields - 1 ? "" : " ");

- trace_seq_printf(s, print_fmt, se->fields[i]->name,
- entry->fields[n_u64],
- i == se->n_fields - 1 ? "" : " ");
+ print_synth_event_num_val(s, print_fmt,
+ se->fields[i]->name,
+ se->fields[i]->size,
+ entry->fields[n_u64],
+ space);

if (strcmp(se->fields[i]->type, "gfp_t") == 0) {
trace_seq_puts(s, " (");
--
2.20.1
\
 
 \ /
  Last update: 2020-03-05 18:15    [W:0.145 / U:28.588 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site