Linux: Use After Free
CVE-2024-27070 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 897761d16564e899faecb9381b4818858705081f, 8186e16a766d709a08f188d2f4e84098f364bea1, eb70d5a6c932d9d23f4bb3e7b83782c21ac4b064 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 897761d16564e899faecb9381b4818858705081f or 8186e16a766d709a08f188d2f4e84098f364bea1 or eb70d5a6c932d9d23f4bb3e7b83782c21ac4b064, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.8.2 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b43c3050d21196e5e7024872e3048dba83e31751 up to, but not including, 897761d16564e899faecb9381b4818858705081f; 87f3afd366f7c668be0269efda8a89741a3ea6b3 up to, but not including, 8186e16a766d709a08f188d2f4e84098f364bea1; 87f3afd366f7c668be0269efda8a89741a3ea6b3 up to, but not including, eb70d5a6c932d9d23f4bb3e7b83782c21ac4b064; 6.8 | 897761d16564e899faecb9381b4818858705081f, 8186e16a766d709a08f188d2f4e84098f364bea1, eb70d5a6c932d9d23f4bb3e7b83782c21ac4b064 |
| Linux | Linux Kernel | 6.8 up to, but not including, 6.8.2 | 6.8.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.1 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid use-after-free issue in f2fs_filemap_fault syzbot reports a f2fs bug as below: BUG: KASAN: slab-use-after-free in f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/file.c:49 Read of size 8 at addr ffff88807bb22680 by task syz-executor184/5058 CPU: 0 PID: 5058 Comm: syz-executor184 Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:377 [inline] print_report+0x163/0x540 mm/kasan/report.c:488 kasan_report+0x142/0x170 mm/kasan/report.c:601 f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/file.c:49 __do_fault+0x131/0x450 mm/memory.c:4376 do_shared_fault mm/memory.c:4798 [inline] do_fault mm/memory.c:4872 [inline] do_pte_missing mm/memory.c:3745 [inline] handle_pte_fault mm/memory.c:5144 [inline] __handle_mm_fault+0x23b7/0x72b0 mm/memory.c:5285 handle_mm_fault+0x27e/0x770 mm/memory.c:5450 do_user_addr_fault arch/x86/mm/fault.c:1364 [inline] handle_page_fault arch/x86/mm/fault.c:1507 [inline] exc_page_fault+0x456/0x870 arch/x86/mm/fault.c:1563 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570 The root cause is: in f2fs_filemap_fault(), vmf->vma may be not alive after filemap_fault(), so it may cause use-after-free issue when accessing vmf->vma->vm_flags in trace_f2fs_filemap_fault(). So it needs to keep vm_flags in separated temporary variable for tracepoint use.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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