Linux: Use After Free
CVE-2022-48925 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 5b1cef5798b4fd6e4fd5522e7b8a26248beeacaa, 00265efbd3e5705038c9492a434fda8cf960c8a2, d350724795c7a48b05bf921d94699fbfecf7da0b 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 0.22% 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 5b1cef5798b4fd6e4fd5522e7b8a26248beeacaa or 00265efbd3e5705038c9492a434fda8cf960c8a2 or d350724795c7a48b05bf921d94699fbfecf7da0b or 22e9f71072fa605cbf033158db58e0790101928d, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.103 or 5.15.26 or 5.16.12, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 732d41c545bb359cbb8c94698bdc1f8bcf82279c up to, but not including, 5b1cef5798b4fd6e4fd5522e7b8a26248beeacaa; 732d41c545bb359cbb8c94698bdc1f8bcf82279c up to, but not including, 00265efbd3e5705038c9492a434fda8cf960c8a2; 732d41c545bb359cbb8c94698bdc1f8bcf82279c up to, but not including, d350724795c7a48b05bf921d94699fbfecf7da0b; 732d41c545bb359cbb8c94698bdc1f8bcf82279c up to, but not including, 22e9f71072fa605cbf033158db58e0790101928d; 5.10 | 5b1cef5798b4fd6e4fd5522e7b8a26248beeacaa, 00265efbd3e5705038c9492a434fda8cf960c8a2, d350724795c7a48b05bf921d94699fbfecf7da0b, 22e9f71072fa605cbf033158db58e0790101928d |
| Linux | Linux Kernel | 5.10 up to, but not including, 5.10.103; 5.11 up to, but not including, 5.15.26; 5.16 up to, but not including, 5.16.12 | 5.10.103, 5.15.26, 5.16.12 |
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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: RDMA/cma: Do not change route.addr.src_addr outside state checks If the state is not idle then resolve_prepare_src() should immediately fail and no change to global state should happen. However, it unconditionally overwrites the src_addr trying to build a temporary any address. For instance if the state is already RDMA_CM_LISTEN then this will corrupt the src_addr and would cause the test in cma_cancel_operation(): if (cma_any_addr(cma_src_addr(id_priv)) && !id_priv->cma_dev) Which would manifest as this trace from syzkaller: BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26 Read of size 8 at addr ffff8881546491e0 by task syz-executor.1/32204 CPU: 1 PID: 32204 Comm: syz-executor.1 Not tainted 5.12.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416 __list_add_valid+0x93/0xa0 lib/list_debug.c:26 __list_add include/linux/list.h:67 [inline] list_add_tail include/linux/list.h:100 [inline] cma_listen_on_all drivers/infiniband/core/cma.c:2557 [inline] rdma_listen+0x787/0xe00 drivers/infiniband/core/cma.c:3751 ucma_listen+0x16a/0x210 drivers/infiniband/core/ucma.c:1102 ucma_write+0x259/0x350 drivers/infiniband/core/ucma.c:1732 vfs_write+0x28e/0xa30 fs/read_write.c:603 ksys_write+0x1ee/0x250 fs/read_write.c:658 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae This is indicating that an rdma_id_private was destroyed without doing cma_cancel_listens(). Instead of trying to re-use the src_addr memory to indirectly create an any address derived from the dst build one explicitly on the stack and bind to that as any other normal flow would do. rdma_bind_addr() will copy it over the src_addr once it knows the state is valid. This is similar to commit bc0bdc5afaa7 ("RDMA/cma: Do not change route.addr.src_addr.ss_family")
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
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
Spotted an error? Tell us.