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 d860351b9dea60d3b6296af9d46d5e2f8fadc9d3..12a735bd90a568471ef22cc684d09bd01d624153 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -3419,7 +3419,7 @@ 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;
        }