blob: 38dc06e68cd1eff4cf7eac00bb92c5fdf0554bd3 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
|
semantic: 0.995
graphic: 0.860
device: 0.736
vnc: 0.420
boot: 0.411
debug: 0.352
permissions: 0.340
socket: 0.263
network: 0.171
other: 0.159
PID: 0.153
performance: 0.140
files: 0.125
KVM: 0.083
x86 BEXTR semantic bug
Description of problem:
The result of instruction BEXTR is different with from the CPU. The value of destination register is different. I think QEMU does not consider the operand size limit.
Steps to reproduce:
1. Compile this code
```
void main() {
asm("mov rax, 0x17b3693f77fb6e9");
asm("mov rbx, 0x8f635a775ad3b9b4");
asm("mov rcx, 0xb717b75da9983018");
asm("bextr eax, ebx, ecx");
}
```
2. Execute and compare the result with the CPU.
- CPU
- RAX = 0x5a
- QEMU
- RAX = 0x635a775a
Additional information:
This bug is discovered by research conducted by KAIST SoftSec.
|