tracing/kprobe: Fix NULL pointer deref check

Add NULL check for avoiding NULL pointer deref.
This bug has been introduced by:

  1ff511e35ed8: tracing/kprobes: Add bitfield type

which causes a null pointer dereference bug when kprobe-tracer
parses an argument without type.

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20110214054807.8919.69740.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index ccdc542022c3..8435b43b1782 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,