perf/core: Fix address filter parser

The token table passed into match_token() must be null-terminated, which
it currently is not in the perf's address filter string parser, as caught
by Vince's perf_fuzzer and KASAN.

It doesn't blow up otherwise because of the alignment padding of the table
to the next element in the .rodata, which is luck.

Fixing by adding a null-terminator to the token table.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dvyukov@google.com
Cc: stable@vger.kernel.org # v4.7+
Fixes: 375637bc52 ("perf/core: Introduce address range filtering")
Link: http://lkml.kernel.org/r/877f81f264.fsf@ashishki-desk.ger.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/events/core.c

@@ -8029,6 +8029,7 @@ restart:
  * if <size> is not specified, the range is treated as a single address.
  */
 enum {
+	IF_ACT_NONE = -1,
 	IF_ACT_FILTER,
 	IF_ACT_START,
 	IF_ACT_STOP,
@@ -8052,6 +8053,7 @@ static const match_table_t if_tokens = {
 	{ IF_SRC_KERNEL,	"%u/%u" },
 	{ IF_SRC_FILEADDR,	"%u@%s" },
 	{ IF_SRC_KERNELADDR,	"%u" },
+	{ IF_ACT_NONE,		NULL },
 };
 
 /*