UBUNTU-CVE-2024-26603
In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Stop relying on userspace for info to fault in xsave buffer Before this change, the expected size of the user space buffer was taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed from user-space, so it is possible construct a sigreturn frame where: * fx_sw->xstate_size is smaller than the size required by valid bits in fx_sw->xfeatures. * user-space unmaps parts of the sigrame fpu buffer so that not all of the buffer required by xrstor is accessible. In this case, xrstor tries to restore and accesses the unmapped area which results in a fault. But fault_in_readable succeeds because buf + fx_sw->xstate_size is within the still mapped area, so it goes back and tries xrstor again. It will spin in this loop forever. Instead, fault in the maximum size which can be touched by XRSTOR (taken from fpstate->user_size). [ dhansen: tweak subject / changelog ]
02 / AFFECTED SOFTWARE
Affected packages
9 explicit affected versions
29 explicit affected versions
43 explicit affected versions
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
18 explicit affected versions
6 explicit affected versions
52 explicit affected versions
38 explicit affected versions
49 explicit affected versions
38 explicit affected versions
10 explicit affected versions
45 explicit affected versions
7 explicit affected versions
46 explicit affected versions
11 explicit affected versions
35 explicit affected versions
5 explicit affected versions
14 explicit affected versions
18 explicit affected versions
7 explicit affected versions
33 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
21 explicit affected versions
9 explicit affected versions
16 explicit affected versions
10 explicit affected versions
7 explicit affected versions
12 explicit affected versions
36 explicit affected versions
12 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
12 explicit affected versions
10 explicit affected versions
37 explicit affected versions
11 explicit affected versions
10 explicit affected versions
25 explicit affected versions
26 explicit affected versions
13 explicit affected versions
4 explicit affected versions
29 explicit affected versions
13 explicit affected versions
49 explicit affected versions
47 explicit affected versions
9 explicit affected versions
33 explicit affected versions
23 explicit affected versions
10 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
37 explicit affected versions
30 explicit affected versions
46 explicit affected versions
10 explicit affected versions
26 explicit affected versions
1 explicit affected versions
13 explicit affected versions
16 explicit affected versions
49 explicit affected versions
39 explicit affected versions
3 explicit affected versions
2 explicit affected versions
51 explicit affected versions
1 explicit affected versions
12 explicit affected versions
35 explicit affected versions
27 explicit affected versions
21 explicit affected versions
8 explicit affected versions
10 explicit affected versions
5 explicit affected versions
8 explicit affected versions
10 explicit affected versions
11 explicit affected versions
13 explicit affected versions
7 explicit affected versions
41 explicit affected versions
10 explicit affected versions
12 explicit affected versions
12 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
35 explicit affected versions
37 explicit affected versions
12 explicit affected versions
38 explicit affected versions
39 explicit affected versions
9 explicit affected versions
38 explicit affected versions
11 explicit affected versions
46 explicit affected versions
8 explicit affected versions
7 explicit affected versions
20 explicit affected versions
4 explicit affected versions
1 explicit affected versions
1 explicit affected versions
44 explicit affected versions
11 explicit affected versions
43 explicit affected versions
10 explicit affected versions
8 explicit affected versions
14 explicit affected versions
4 explicit affected versions
9 explicit affected versions
1 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Stop relying on userspace for info to fault in xsave buffer Before this change, the expected size of the user space buffer was taken from fx_sw->xstate_size. fx_sw->xstate_size can be changed from user-space, so it is possible construct a sigreturn frame where: * fx_sw->xstate_size is smaller than the size required by valid bits in fx_sw->xfeatures. * user-space unmaps parts of the sigrame fpu buffer so that not all of the buffer required by xrstor is accessible. In this case, xrstor tries to restore and accesses the unmapped area which results in a fault. But fault_in_readable succeeds because buf + fx_sw->xstate_size is within the still mapped area, so it goes back and tries xrstor again. It will spin in this loop forever. Instead, fault in the maximum size which can be touched by XRSTOR (taken from fpstate->user_size). [ dhansen: tweak subject / changelog ]
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/d877550eaf2dc9090d782864c96939397a3c6835
- https://ubuntu.com/security/CVE-2024-26603
- https://ubuntu.com/security/notices/USN-6820-1
- https://ubuntu.com/security/notices/USN-6820-2
- https://ubuntu.com/security/notices/USN-6821-1
- https://ubuntu.com/security/notices/USN-6821-2
- https://ubuntu.com/security/notices/USN-6821-3
- https://ubuntu.com/security/notices/USN-6821-4
- https://ubuntu.com/security/notices/USN-6828-1
- https://ubuntu.com/security/notices/USN-6871-1
- https://ubuntu.com/security/notices/USN-6892-1
- https://ubuntu.com/security/notices/USN-6895-1
- https://ubuntu.com/security/notices/USN-6895-2
- https://ubuntu.com/security/notices/USN-6895-3
- https://ubuntu.com/security/notices/USN-6895-4
- https://ubuntu.com/security/notices/USN-6900-1
- https://ubuntu.com/security/notices/USN-6919-1
- https://www.cve.org/CVERecord?id=CVE-2024-26603