Due to incorrect string size calculations inside the preg_quote function, a large input string passed to the function can trigger an integer overflow leading to a heap overflow. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
| Link | Tags |
|---|---|
| https://hhvm.com/blog/2021/02/25/security-update.html | third party advisory release notes |
| https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca | third party advisory patch |