perf annotate: Check if offset is less than symbol size

Just like done on symbol__inc_addr_samples to catch misparsed offsets
from objdump.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/annotate.c

@@ -541,11 +541,12 @@ void symbol__annotate_decay_histogram(struct symbol *sym, int evidx)
 	struct annotation *notes = symbol__annotation(sym);
 	struct sym_hist *h = annotation__histogram(notes, evidx);
 	struct objdump_line *pos;
+	int len = sym->end - sym->start;
 
 	h->sum = 0;
 
 	list_for_each_entry(pos, &notes->src->source, node) {
-		if (pos->offset != -1) {
+		if (pos->offset != -1 && pos->offset < len) {
 			h->addr[pos->offset] = h->addr[pos->offset] * 7 / 8;
 			h->sum += h->addr[pos->offset];
 		}