[PATCH -tip ] [BUGFIX] tracing/kprobe: Fix NULL pointer deref check

[Masami Hiramatsu]

Add NULL check for avoiding NULL pointer deref.
This bug has been introduced by
1ff511e35ed87cc2ebade9e678e4a2fe39b6f9c5, which causes
a null pointer dereference bug when kprobe-tracer parses
an argument without type.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---

 kernel/trace/trace_kprobe.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ccdc542..8435b43 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -935,7 +935,7 @@ static int parse_probe_arg(char *arg, struct trace_probe *tp,
 	parg->offset = tp->size;
 	tp->size += parg->type->size;
 	ret = __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
-	if (ret >= 0)
+	if (ret >= 0 && t != NULL)
 		ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
 	if (ret >= 0) {
 		parg->fetch_size.fn = get_fetch_size_function(parg->type,

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