From: Masami Hiramatsu <mhiramat@xxxxxxxxxx> commit 3dd1f7f24f8ceec00bbbc364c2ac3c893f0fdc4c upstream. Fix to make the type of $comm "string". If we set the other type to $comm argument, it shows meaningless value or wrong data. Currently probe events allow us to set string array type (e.g. ":string[2]"), or other digit types like x8 on $comm. But since clearly $comm is just a string data, it should not be fetched by other types including array. Link: http://lkml.kernel.org/r/155723736241.9149.14582064184468574539.stgit@devnote2 Cc: Andreas Ziegler <andreas.ziegler@xxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code") Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace_probe.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -420,13 +420,14 @@ static int traceprobe_parse_probe_arg_bo return -E2BIG; } } - /* - * The default type of $comm should be "string", and it can't be - * dereferenced. - */ - if (!t && strcmp(arg, "$comm") == 0) + + /* Since $comm can not be dereferred, we can find $comm by strcmp */ + if (strcmp(arg, "$comm") == 0) { + /* The type of $comm must be "string", and not an array. */ + if (parg->count || (t && strcmp(t, "string"))) + return -EINVAL; parg->type = find_fetch_type("string"); - else + } else parg->type = find_fetch_type(t); if (!parg->type) { pr_info("Unsupported type: %s\n", t);
