objtool: Fix memory leak in decode_instructions()

When an error occurs before adding an allocated insn to the list, free
it before returning.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/336da800bf6070eae11f4e0a3b9ca64c27658114.1508430423.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/objtool/check.c

@@ -267,12 +267,13 @@ static int decode_instructions(struct objtool_file *file)
 						      &insn->immediate,
 						      &insn->stack_op);
 			if (ret)
-				return ret;
+				goto err;
 
 			if (!insn->type || insn->type > INSN_LAST) {
 				WARN_FUNC("invalid instruction type %d",
 					  insn->sec, insn->offset, insn->type);
-				return -1;
+				ret = -1;
+				goto err;
 			}
 
 			hash_add(file->insn_hash, &insn->hash, insn->offset);
@@ -296,6 +297,10 @@ static int decode_instructions(struct objtool_file *file)
 	}
 
 	return 0;
+
+err:
+	free(insn);
+	return ret;
 }
 
 /*