reject short sourcemap and symbolmap entries in janet_asm1 (#1927)

src/core/asm.c

@@ -721,6 +721,9 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
                 janet_asm_error(&a, "expected tuple");
             }
             tup = janet_unwrap_tuple(entry);
+            if (janet_tuple_length(tup) < 2) {
+                janet_asm_error(&a, "sourcemap entry must have 2 elements");
+            }
             if (!janet_checkint(tup[0])) {
                 janet_asm_error(&a, "expected integer");
             }
@@ -751,6 +754,9 @@ static JanetAssembleResult janet_asm1(JanetAssembler *parent, Janet source, int
                 janet_asm_error(&a, "expected tuple");
             }
             tup = janet_unwrap_tuple(entry);
+            if (janet_tuple_length(tup) < 4) {
+                janet_asm_error(&a, "symbolmap entry must have 4 elements");
+            }
             if (janet_keyeq(tup[0], "upvalue")) {
                 ss.birth_pc = UINT32_MAX;
             } else if (!janet_checkint(tup[0])) {

test/suite-asm.janet

@@ -66,5 +66,9 @@
 (def optimized (disasm (asm ~{:bytecode [(ldi 0 10) (movn 1 0) (add 2 0 1) (add 3 1 1) (add 4 0 0) (add 5 2 3) (ret 5)] :slotcount 40} :o) :bytecode))
 (assert (deep= optimized '@[(ldi 0 40) (ret 0)]) "bytecode optimization 1")
 
+# short sourcemap/symbolmap entries must not read past the tuple
+(assert-error "short sourcemap entry" (asm '{:arity 0 :bytecode [(ret 0)] :sourcemap [[1]]}))
+(assert-error "short symbolmap entry" (asm '{:arity 0 :bytecode [(ret 0)] :symbolmap [[1 2 3]]}))
+
 (end-suite)