diff options
| author | Wen Yang <wenyang@linux.alibaba.com> | 2020-01-03 11:02:48 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-09 10:19:03 +0100 |
| commit | 010a7e846d4beaf34384c40ff18d5de10106d9b4 (patch) | |
| tree | d168bdc2ccb2ce1dc8818e08877b4707ca216c2c | |
| parent | d89a351b082e52c44e1c6537c7ef75fd8c901bde (diff) | |
ftrace: Avoid potential division by zero in function profiler
commit e31f7939c1c27faa5d0e3f14519eaf7c89e8a69d upstream.
The ftrace_profile->counter is unsigned long and
do_div truncates it to 32 bits, which means it can test
non-zero and be truncated to zero for division.
Fix this issue by using div64_ul() instead.
Link: http://lkml.kernel.org/r/20200103030248.14516-1-wenyang@linux.alibaba.com
Cc: stable@vger.kernel.org
Fixes: e330b3bcd8319 ("tracing: Show sample std dev in function profiling")
Fixes: 34886c8bc590f ("tracing: add average time in function to function profiler")
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/trace/ftrace.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b84eb9659e95..37a435bac161 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -554,8 +554,7 @@ static int function_stat_show(struct seq_file *m, void *v) } #ifdef CONFIG_FUNCTION_GRAPH_TRACER - avg = rec->time; - do_div(avg, rec->counter); + avg = div64_ul(rec->time, rec->counter); if (tracing_thresh && (avg < tracing_thresh)) goto out; #endif @@ -581,7 +580,8 @@ static int function_stat_show(struct seq_file *m, void *v) * Divide only 1000 for ns^2 -> us^2 conversion. * trace_print_graph_duration will divide 1000 again. */ - do_div(stddev, rec->counter * (rec->counter - 1) * 1000); + stddev = div64_ul(stddev, + rec->counter * (rec->counter - 1) * 1000); } trace_seq_init(&s); |