blob: 3d1539efab01df81fd9150dd24bd367030af45e6 (
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
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
x86: 1.000
assembly: 0.991
semantic: 0.982
i386: 0.980
debug: 0.687
register: 0.219
user-level: 0.151
operating system: 0.067
virtual: 0.044
files: 0.029
kernel: 0.023
hypervisor: 0.017
performance: 0.017
TCG: 0.016
architecture: 0.009
PID: 0.008
peripherals: 0.007
device: 0.007
network: 0.006
alpha: 0.003
risc-v: 0.003
VMM: 0.003
permissions: 0.002
socket: 0.002
KVM: 0.002
graphic: 0.002
boot: 0.002
ppc: 0.001
vnc: 0.001
mistranslation: 0.001
arm: 0.000
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
Compile this code
void main() {
asm("mov rax, 0x17b3693f77fb6e9");
asm("mov rbx, 0x8f635a775ad3b9b4");
asm("mov rcx, 0xb717b75da9983018");
asm("bextr eax, ebx, ecx");
}
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.
|