From: "Steven Rostedt (Google)" rostedt@goodmis.org
The variable $comm is hard coded as a string, which is true for both kprobes and uprobes, but for event probes (eprobes) it is a field name. In most cases the "comm" field would be a string, but there's no guarantee of that fact.
Do not assume that comm is a string. Not to mention, it currently forces comm fields to fault, as string processing for event probes is currently broken.
Cc: stable@vger.kernel.org Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events") Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- kernel/trace/trace_probe.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index dec657af363c..4daabbb8b772 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -622,9 +622,10 @@ static int traceprobe_parse_probe_arg_body(const char *argv, ssize_t *size,
/* * Since $comm and immediate string can not be dereferenced, - * we can find those by strcmp. + * we can find those by strcmp. But ignore for eprobes. */ - if (strcmp(arg, "$comm") == 0 || strncmp(arg, "\"", 2) == 0) { + if (!(flags & TPARG_FL_TPOINT) && + (strcmp(arg, "$comm") == 0 || strncmp(arg, "\"", 2) == 0)) { /* The type of $comm must be "string", and not an array. */ if (parg->count || (t && strcmp(t, "string"))) goto out;