Add RegExp recursion depth limit (#2543)

The regexp engine does not have any recursion depth check, thus it can cause problems with various regexps. Added a new build option `--regexp-recursion-limit N` whose
default value is 0, which is for unlimited recursion depth. Also added a build-option-test.

Fixes #2448
Fixes #2190

JerryScript-DCO-1.0-Signed-off-by: Istvan Miklos imiklos2@inf.u-szeged.hu

jerry-core/parser/regexp/re-compiler.c

@@ -246,6 +246,7 @@ static ecma_value_t
 re_parse_alternative (re_compiler_ctx_t *re_ctx_p, /**< RegExp compiler context */
                       bool expect_eof) /**< expect end of file */
 {
+  REGEXP_RECURSION_COUNTER_DECREASE_AND_TEST ();
   uint32_t idx;
   re_bytecode_ctx_t *bc_ctx_p = re_ctx_p->bytecode_ctx_p;
   ecma_value_t ret_value = ECMA_VALUE_EMPTY;
@@ -440,6 +441,7 @@ re_parse_alternative (re_compiler_ctx_t *re_ctx_p, /**< RegExp compiler context
         else
         {
           re_insert_u32 (bc_ctx_p, alterantive_offset, re_get_bytecode_length (bc_ctx_p) - alterantive_offset);
+          REGEXP_RECURSION_COUNTER_INCREASE ();
           should_loop = false;
         }
         break;
@@ -453,6 +455,7 @@ re_parse_alternative (re_compiler_ctx_t *re_ctx_p, /**< RegExp compiler context
         else
         {
           re_insert_u32 (bc_ctx_p, alterantive_offset, re_get_bytecode_length (bc_ctx_p) - alterantive_offset);
+          REGEXP_RECURSION_COUNTER_INCREASE ();
           should_loop = false;
         }
 
@@ -559,6 +562,7 @@ re_compile_bytecode (const re_compiled_code_t **out_bytecode_p, /**< [out] point
   re_ctx.flags = flags;
   re_ctx.highest_backref = 0;
   re_ctx.num_of_non_captures = 0;
+  REGEXP_RECURSION_COUNTER_INIT ();
 
   re_bytecode_ctx_t bc_ctx;
   bc_ctx.block_start_p = NULL;

jerry-core/parser/regexp/re-compiler.h

@@ -41,6 +41,9 @@ typedef struct
   uint32_t num_of_captures;          /**< number of capture groups */
   uint32_t num_of_non_captures;      /**< number of non-capture groups */
   uint32_t highest_backref;          /**< highest backreference */
+#ifdef REGEXP_RECURSION_LIMIT
+  uint32_t recursion_counter;        /**< RegExp recursion counter */
+#endif /* REGEXP_RECURSION_LIMIT */
   re_bytecode_ctx_t *bytecode_ctx_p; /**< pointer of RegExp bytecode context */
   re_token_t current_token;          /**< current token */
   re_parser_ctx_t *parser_ctx_p;     /**< pointer of RegExp parser context */