Fix memory leak in stk_base when Regexp timeout

[Bug #20228]

If rb_reg_check_timeout raises a Regexp::TimeoutError, then the stk_base
will leak.

re.c

@@ -4605,8 +4605,8 @@ re_warn(const char *s)
 rb_hrtime_t rb_reg_match_time_limit = 0;
 
 // This function is periodically called during regexp matching
-void
-rb_reg_check_timeout(regex_t *reg, void *end_time_)
+bool
+rb_reg_timeout_p(regex_t *reg, void *end_time_)
 {
     rb_hrtime_t *end_time = (rb_hrtime_t *)end_time_;
 
@@ -4631,10 +4631,18 @@ rb_reg_check_timeout(regex_t *reg, void *end_time_)
     }
     else {
         if (*end_time < rb_hrtime_now()) {
-            // timeout is exceeded
-            rb_raise(rb_eRegexpTimeoutError, "regexp match timeout");
+            // Timeout has exceeded
+            return true;
         }
     }
+
+    return false;
+}
+
+void
+rb_reg_raise_timeout(void)
+{
+    rb_raise(rb_eRegexpTimeoutError, "regexp match timeout");
 }
 
 /*

regexec.c

@@ -2293,7 +2293,7 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   UChar *pkeep;
   char *alloca_base;
   char *xmalloc_base = NULL;
-  OnigStackType *stk_alloc, *stk_base, *stk, *stk_end;
+  OnigStackType *stk_alloc, *stk_base = NULL, *stk, *stk_end;
   OnigStackType *stkp; /* used as any purpose. */
   OnigStackIndex si;
   OnigStackIndex *repeat_stk;
@@ -4202,6 +4202,11 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
   STACK_SAVE;
   xfree(xmalloc_base);
   return ONIGERR_UNEXPECTED_BYTECODE;
+
+ timeout:
+  xfree(xmalloc_base);
+  xfree(stk_base);
+  HANDLE_REG_TIMEOUT_IN_MATCH_AT;
 }
 
 

regint.h

@@ -154,13 +154,18 @@
 #ifdef RUBY
 
 # define CHECK_INTERRUPT_IN_MATCH_AT do { \
-  msa->counter++;                         \
-  if (msa->counter >= 128) {              \
-    msa->counter = 0;                     \
-    rb_reg_check_timeout(reg, &msa->end_time);  \
-    rb_thread_check_ints();               \
-  }                                       \
+  msa->counter++; \
+  if (msa->counter >= 128) { \
+    msa->counter = 0; \
+    if (rb_reg_timeout_p(reg, &msa->end_time)) { \
+      goto timeout; \
+    } \
+    rb_thread_check_ints(); \
+  } \
 } while(0)
+# define HANDLE_REG_TIMEOUT_IN_MATCH_AT do { \
+  rb_reg_raise_timeout(); \
+} while (0)
 # define onig_st_init_table                  st_init_table
 # define onig_st_init_table_with_size        st_init_table_with_size
 # define onig_st_init_numtable               st_init_numtable
@@ -996,7 +1001,8 @@ extern int onig_st_insert_strend(hash_table_type* table, const UChar* str_key, c
 #ifdef RUBY
 extern size_t onig_memsize(const regex_t *reg);
 extern size_t onig_region_memsize(const struct re_registers *regs);
-void rb_reg_check_timeout(regex_t *reg, void *end_time);
+bool rb_reg_timeout_p(regex_t *reg, void *end_time);
+NORETURN(void rb_reg_raise_timeout(void));
 #endif
 
 RUBY_SYMBOL_EXPORT_END