UBUNTU-CVE-2025-22090
In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range() If track_pfn_copy() fails, we already added the dst VMA to the maple tree. As fork() fails, we'll cleanup the maple tree, and stumble over the dst VMA for which we neither performed any reservation nor copied any page tables. Consequently untrack_pfn() will see VM_PAT and try obtaining the PAT information from the page table -- which fails because the page table was not copied. The easiest fix would be to simply clear the VM_PAT flag of the dst VMA if track_pfn_copy() fails. However, the whole thing is about "simply" clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy() and performed a reservation, but copying the page tables fails, we'll simply clear the VM_PAT flag, not properly undoing the reservation ... which is also wrong. So let's fix it properly: set the VM_PAT flag only if the reservation succeeded (leaving it clear initially), and undo the reservation if anything goes wrong while copying the page tables: clearing the VM_PAT flag after undoing the reservation. Note that any copied page table entries will get zapped when the VMA will get removed later, after copy_page_range() succeeded; as VM_PAT is not set then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be happy. Note that leaving these page tables in place without a reservation is not a problem, as we are aborting fork(); this process will never run. A reproducer can trigger this usually at the first try: https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110 Modules linked in: ... CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:get_pat_info+0xf6/0x110 ... Call Trace: <TASK> ... untrack_pfn+0x52/0x110 unmap_single_vma+0xa6/0xe0 unmap_vmas+0x105/0x1f0 exit_mmap+0xf6/0x460 __mmput+0x4b/0x120 copy_process+0x1bf6/0x2aa0 kernel_clone+0xab/0x440 __do_sys_clone+0x66/0x90 do_syscall_64+0x95/0x180 Likely this case was missed in: d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed") ... and instead of undoing the reservation we simply cleared the VM_PAT flag. Keep the documentation of these functions in include/linux/pgtable.h, one place is more than sufficient -- we should clean that up for the other functions like track_pfn_remap/untrack_pfn separately.
02 / AFFECTED SOFTWARE
Affected packages
11 explicit affected versions
53 explicit affected versions
116 explicit affected versions
89 explicit affected versions
50 explicit affected versions
6 explicit affected versions
12 explicit affected versions
19 explicit affected versions
6 explicit affected versions
100 explicit affected versions
24 explicit affected versions
85 explicit affected versions
84 explicit affected versions
91 explicit affected versions
86 explicit affected versions
76 explicit affected versions
10 explicit affected versions
23 explicit affected versions
26 explicit affected versions
90 explicit affected versions
191 explicit affected versions
7 explicit affected versions
7 explicit affected versions
84 explicit affected versions
27 explicit affected versions
13 explicit affected versions
85 explicit affected versions
12 explicit affected versions
30 explicit affected versions
35 explicit affected versions
51 explicit affected versions
50 explicit affected versions
32 explicit affected versions
120 explicit affected versions
18 explicit affected versions
42 explicit affected versions
118 explicit affected versions
64 explicit affected versions
13 explicit affected versions
4 explicit affected versions
121 explicit affected versions
23 explicit affected versions
38 explicit affected versions
34 explicit affected versions
124 explicit affected versions
1 explicit affected versions
1 explicit affected versions
21 explicit affected versions
16 explicit affected versions
10 explicit affected versions
76 explicit affected versions
6 explicit affected versions
111 explicit affected versions
6 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
5 explicit affected versions
104 explicit affected versions
12 explicit affected versions
105 explicit affected versions
12 explicit affected versions
27 explicit affected versions
120 explicit affected versions
45 explicit affected versions
21 explicit affected versions
20 explicit affected versions
10 explicit affected versions
37 explicit affected versions
8 explicit affected versions
13 explicit affected versions
26 explicit affected versions
10 explicit affected versions
68 explicit affected versions
1 explicit affected versions
26 explicit affected versions
2 explicit affected versions
13 explicit affected versions
111 explicit affected versions
144 explicit affected versions
37 explicit affected versions
1 explicit affected versions
29 explicit affected versions
13 explicit affected versions
96 explicit affected versions
27 explicit affected versions
27 explicit affected versions
1 explicit affected versions
100 explicit affected versions
92 explicit affected versions
55 explicit affected versions
33 explicit affected versions
23 explicit affected versions
60 explicit affected versions
10 explicit affected versions
6 explicit affected versions
188 explicit affected versions
5 explicit affected versions
11 explicit affected versions
12 explicit affected versions
7 explicit affected versions
12 explicit affected versions
138 explicit affected versions
2 explicit affected versions
77 explicit affected versions
132 explicit affected versions
93 explicit affected versions
165 explicit affected versions
154 explicit affected versions
10 explicit affected versions
26 explicit affected versions
28 explicit affected versions
1 explicit affected versions
69 explicit affected versions
21 explicit affected versions
33 explicit affected versions
13 explicit affected versions
32 explicit affected versions
139 explicit affected versions
78 explicit affected versions
16 explicit affected versions
91 explicit affected versions
36 explicit affected versions
116 explicit affected versions
3 explicit affected versions
132 explicit affected versions
93 explicit affected versions
1 explicit affected versions
5 explicit affected versions
2 explicit affected versions
51 explicit affected versions
92 explicit affected versions
15 explicit affected versions
28 explicit affected versions
12 explicit affected versions
71 explicit affected versions
80 explicit affected versions
27 explicit affected versions
66 explicit affected versions
121 explicit affected versions
1 explicit affected versions
1 explicit affected versions
98 explicit affected versions
29 explicit affected versions
8 explicit affected versions
55 explicit affected versions
5 explicit affected versions
3 explicit affected versions
8 explicit affected versions
1 explicit affected versions
10 explicit affected versions
5 explicit affected versions
32 explicit affected versions
13 explicit affected versions
110 explicit affected versions
13 explicit affected versions
72 explicit affected versions
7 explicit affected versions
140 explicit affected versions
5 explicit affected versions
94 explicit affected versions
10 explicit affected versions
12 explicit affected versions
39 explicit affected versions
108 explicit affected versions
80 explicit affected versions
56 explicit affected versions
44 explicit affected versions
16 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
45 explicit affected versions
37 explicit affected versions
37 explicit affected versions
14 explicit affected versions
38 explicit affected versions
167 explicit affected versions
9 explicit affected versions
11 explicit affected versions
25 explicit affected versions
8 explicit affected versions
92 explicit affected versions
7 explicit affected versions
97 explicit affected versions
121 explicit affected versions
4 explicit affected versions
81 explicit affected versions
1 explicit affected versions
1 explicit affected versions
1 explicit affected versions
91 explicit affected versions
80 explicit affected versions
79 explicit affected versions
13 explicit affected versions
8 explicit affected versions
43 explicit affected versions
77 explicit affected versions
119 explicit affected versions
10 explicit affected versions
31 explicit affected versions
88 explicit affected versions
14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
69 explicit affected versions
123 explicit affected versions
5 explicit affected versions
25 explicit affected versions
80 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range() If track_pfn_copy() fails, we already added the dst VMA to the maple tree. As fork() fails, we'll cleanup the maple tree, and stumble over the dst VMA for which we neither performed any reservation nor copied any page tables. Consequently untrack_pfn() will see VM_PAT and try obtaining the PAT information from the page table -- which fails because the page table was not copied. The easiest fix would be to simply clear the VM_PAT flag of the dst VMA if track_pfn_copy() fails. However, the whole thing is about "simply" clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy() and performed a reservation, but copying the page tables fails, we'll simply clear the VM_PAT flag, not properly undoing the reservation ... which is also wrong. So let's fix it properly: set the VM_PAT flag only if the reservation succeeded (leaving it clear initially), and undo the reservation if anything goes wrong while copying the page tables: clearing the VM_PAT flag after undoing the reservation. Note that any copied page table entries will get zapped when the VMA will get removed later, after copy_page_range() succeeded; as VM_PAT is not set then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be happy. Note that leaving these page tables in place without a reservation is not a problem, as we are aborting fork(); this process will never run. A reproducer can trigger this usually at the first try: https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110 Modules linked in: ... CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:get_pat_info+0xf6/0x110 ... Call Trace: <TASK> ... untrack_pfn+0x52/0x110 unmap_single_vma+0xa6/0xe0 unmap_vmas+0x105/0x1f0 exit_mmap+0xf6/0x460 __mmput+0x4b/0x120 copy_process+0x1bf6/0x2aa0 kernel_clone+0xab/0x440 __do_sys_clone+0x66/0x90 do_syscall_64+0x95/0x180 Likely this case was missed in: d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed") ... and instead of undoing the reservation we simply cleared the VM_PAT flag. Keep the documentation of these functions in include/linux/pgtable.h, one place is more than sufficient -- we should clean that up for the other functions like track_pfn_remap/untrack_pfn separately.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/dc84bc2aba85a1508f04a936f9f9a15f64ebfb31
- https://git.kernel.org/stable/c/8d6373f83f367dbed316ddeb178130a3a64b5b67
- https://git.kernel.org/stable/c/b07398e8a5da517083f5c3f2daa8f6681b48ab28
- https://git.kernel.org/stable/c/da381c33f3aa6406406c9fdf07b8b0b63e0ce722
- https://git.kernel.org/stable/c/dc84bc2aba85a1508f04a936f9f9a15f64ebfb31
- https://git.kernel.org/stable/c/de6185b8892d88142ef69768fe4077cbf40109c0
- https://ubuntu.com/security/CVE-2025-22090
- https://ubuntu.com/security/notices/USN-7594-1
- https://ubuntu.com/security/notices/USN-7594-2
- https://ubuntu.com/security/notices/USN-7594-3
- https://ubuntu.com/security/notices/USN-7605-1
- https://ubuntu.com/security/notices/USN-7605-2
- https://ubuntu.com/security/notices/USN-7606-1
- https://ubuntu.com/security/notices/USN-7628-1
- https://ubuntu.com/security/notices/USN-7835-1
- https://ubuntu.com/security/notices/USN-7835-2
- https://ubuntu.com/security/notices/USN-7835-3
- https://ubuntu.com/security/notices/USN-7835-4
- https://ubuntu.com/security/notices/USN-7835-5
- https://ubuntu.com/security/notices/USN-7835-6
- https://ubuntu.com/security/notices/USN-7887-1
- https://ubuntu.com/security/notices/USN-7887-2
- https://ubuntu.com/security/notices/USN-7940-1
- https://ubuntu.com/security/notices/USN-7940-2
- https://www.cve.org/CVERecord?id=CVE-2025-22090