tracing/histograms: String compares should not care about signed values

commit 450fec13d9170127678f991698ac1a5b05c02e2f upstream.

When comparing two strings for the "onmatch" histogram trigger, fields
that are strings use string comparisons, which do not care about being
signed or not.

Do not fail to match two string fields if one is unsigned char array and
the other is a signed char array.

Link: https://lore.kernel.org/all/20211129123043.5cfd687a@gandalf.local.home/
Cc: stable@vgerk.kernel.org
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Yafang Shao <laoar.shao@gmail.com>
Fixes: b05e89ae7cf3b ("tracing: Accept different type for synthetic event fields")
Reviewed-by: Masami Hiramatsu <mhiramatsu@kernel.org>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c2ec467..003e5f3 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3344,7 +3344,7 @@ static int check_synth_field(struct synth_event *event,
 
        if (strcmp(field->type, hist_field->type) != 0) {
                if (field->size != hist_field->size ||
-                   field->is_signed != hist_field->is_signed)
+                   (!field->is_string && field->is_signed != hist_field->is_signed))
                        return -EINVAL;
        }