tracing: Remove size restriction on synthetic event cmd error logging

Currently, synthetic event command error strings are restricted to a
length of MAX_FILTER_STR_VAL (256), which is too short for some
commands already seen in the wild (with cmd strings longer than that
showing up truncated in err_log).

Remove the restriction so that no synthetic event command error string
is ever truncated.

Link: https://lkml.kernel.org/r/0376692396a81d0b795127c66ea92ca5bf60f481.1643399022.git.zanussi@kernel.org
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 154db74dadbcba652f874f5404f360db636b02bc..fdd79e07e2fc6178fd843694eb4121306d3d9083 100644 (file)
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -42,10 +42,13 @@ enum { ERRORS };
 
 static const char *err_text[] = { ERRORS };
 
-static char last_cmd[MAX_FILTER_STR_VAL];
+static char *last_cmd;
 
 static int errpos(const char *str)
 {
+       if (!str || !last_cmd)
+               return 0;
+
        return err_pos(last_cmd, str);
 }
 
@@ -54,11 +57,19 @@ static void last_cmd_set(const char *str)
        if (!str)
                return;
 
-       strncpy(last_cmd, str, MAX_FILTER_STR_VAL - 1);
+       kfree(last_cmd);
+       last_cmd = kzalloc(strlen(str) + 1, GFP_KERNEL);
+       if (!last_cmd)
+               return;
+
+       strncpy(last_cmd, str, strlen(str) + 1);
 }
 
-static void synth_err(u8 err_type, u8 err_pos)
+static void synth_err(u8 err_type, u16 err_pos)
 {
+       if (!last_cmd)
+               return;
+
        tracing_log_err(NULL, "synthetic_events", last_cmd, err_text,
                        err_type, err_pos);
 }