Linux: Use After Free
CVE-2024-41057 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.0 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 8de253177112a47c9af157d23ae934779188b4e1, 9e67589a4a7b7e5660b524d1d5fe61242bcbcc11, ef81340401e8a371d6b17f69e76d861920972cfe 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 0.28% 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 8de253177112a47c9af157d23ae934779188b4e1 or 9e67589a4a7b7e5660b524d1d5fe61242bcbcc11 or ef81340401e8a371d6b17f69e76d861920972cfe or 5d8f805789072ea7fd39504694b7bd17e5f751c4, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.101 or 6.6.42 or 6.9.11, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 up to, but not including, 8de253177112a47c9af157d23ae934779188b4e1; fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 up to, but not including, 9e67589a4a7b7e5660b524d1d5fe61242bcbcc11; fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 up to, but not including, ef81340401e8a371d6b17f69e76d861920972cfe; fe2140e2f57fef8562e0f9b7cd447d2b08dc2f35 up to, but not including, 5d8f805789072ea7fd39504694b7bd17e5f751c4; 5.17 | 8de253177112a47c9af157d23ae934779188b4e1, 9e67589a4a7b7e5660b524d1d5fe61242bcbcc11, ef81340401e8a371d6b17f69e76d861920972cfe, 5d8f805789072ea7fd39504694b7bd17e5f751c4 |
| Linux | Linux Kernel | 5.17 up to, but not including, 6.1.101; 6.2 up to, but not including, 6.6.42; 6.7 up to, but not including, 6.9.11 | 6.1.101, 6.6.42, 6.9.11 |
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
- HighSuccess depends on conditions outside the attacker's control.
- 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:H/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 | 7.0 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie() We got the following issue in our fault injection stress test: ================================================================== BUG: KASAN: slab-use-after-free in cachefiles_withdraw_cookie+0x4d9/0x600 Read of size 8 at addr ffff888118efc000 by task kworker/u78:0/109 CPU: 13 PID: 109 Comm: kworker/u78:0 Not tainted 6.8.0-dirty #566 Call Trace: <TASK> kasan_report+0x93/0xc0 cachefiles_withdraw_cookie+0x4d9/0x600 fscache_cookie_state_machine+0x5c8/0x1230 fscache_cookie_worker+0x91/0x1c0 process_one_work+0x7fa/0x1800 [...] Allocated by task 117: kmalloc_trace+0x1b3/0x3c0 cachefiles_acquire_volume+0xf3/0x9c0 fscache_create_volume_work+0x97/0x150 process_one_work+0x7fa/0x1800 [...] Freed by task 120301: kfree+0xf1/0x2c0 cachefiles_withdraw_cache+0x3fa/0x920 cachefiles_put_unbind_pincount+0x1f6/0x250 cachefiles_daemon_release+0x13b/0x290 __fput+0x204/0xa00 task_work_run+0x139/0x230 do_exit+0x87a/0x29b0 [...] ================================================================== Following is the process that triggers the issue: p1 | p2 ------------------------------------------------------------ fscache_begin_lookup fscache_begin_volume_access fscache_cache_is_live(fscache_cache) cachefiles_daemon_release cachefiles_put_unbind_pincount cachefiles_daemon_unbind cachefiles_withdraw_cache fscache_withdraw_cache fscache_set_cache_state(cache, FSCACHE_CACHE_IS_WITHDRAWN); cachefiles_withdraw_objects(cache) fscache_wait_for_objects(fscache) atomic_read(&fscache_cache->object_count) == 0 fscache_perform_lookup cachefiles_lookup_cookie cachefiles_alloc_object refcount_set(&object->ref, 1); object->volume = volume fscache_count_object(vcookie->cache); atomic_inc(&fscache_cache->object_count) cachefiles_withdraw_volumes cachefiles_withdraw_volume fscache_withdraw_volume __cachefiles_free_volume kfree(cachefiles_volume) fscache_cookie_state_machine cachefiles_withdraw_cookie cache = object->volume->cache; // cachefiles_volume UAF !!! After setting FSCACHE_CACHE_IS_WITHDRAWN, wait for all the cookie lookups to complete first, and then wait for fscache_cache->object_count == 0 to avoid the cookie exiting after the volume has been freed and triggering the above issue. Therefore call fscache_withdraw_volume() before calling cachefiles_withdraw_objects(). This way, after setting FSCACHE_CACHE_IS_WITHDRAWN, only the following two cases will occur: 1) fscache_begin_lookup fails in fscache_begin_volume_access(). 2) fscache_withdraw_volume() will ensure that fscache_count_object() has been executed before calling fscache_wait_for_objects().
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
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