blob: ec7c57fb1adf090aec4e85d3cf9ad5f08485eadd (
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: 0.993
graphic: 0.790
device: 0.717
boot: 0.516
vnc: 0.471
socket: 0.397
network: 0.219
other: 0.099
KVM: 0.091
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.
|