Linux: Use After Free
CVE-2024-35854 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 e118e7ea24d1392878ef85926627c6bc640c4388, a429a912d6c779807f4d72a6cc0a1efaaa3613e1, 4c89642ca47fb620914780c7c51d8d1248201121 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 0.58% 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 e118e7ea24d1392878ef85926627c6bc640c4388 or a429a912d6c779807f4d72a6cc0a1efaaa3613e1 or 4c89642ca47fb620914780c7c51d8d1248201121 or 813e2ab753a8f8c243a39ede20c2e0adc15f3887, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, e118e7ea24d1392878ef85926627c6bc640c4388; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, a429a912d6c779807f4d72a6cc0a1efaaa3613e1; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, 4c89642ca47fb620914780c7c51d8d1248201121; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, 813e2ab753a8f8c243a39ede20c2e0adc15f3887; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, 311eeaa7b9e26aba5b3d57b09859f07d8e9fc049; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, a02687044e124f8ccb427cd3632124a4e1a7d7c1; c9c9af91f1d9a636aecc55302c792538e549a430 up to, but not including, 54225988889931467a9b55fdbef534079b665519; 5.1 | e118e7ea24d1392878ef85926627c6bc640c4388, a429a912d6c779807f4d72a6cc0a1efaaa3613e1, 4c89642ca47fb620914780c7c51d8d1248201121, 813e2ab753a8f8c243a39ede20c2e0adc15f3887, 311eeaa7b9e26aba5b3d57b09859f07d8e9fc049, a02687044e124f8ccb427cd3632124a4e1a7d7c1 |
| Linux | linux_kernel | c9c9af91f1d9; 5.1 | Not stated |
| Debian | Debian Linux | 10.0 | Not stated |
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 CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 8.8 | High | CISA (ADP) |
Official description
In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash The rehash delayed work migrates filters from one region to another according to the number of available credits. The migrated from region is destroyed at the end of the work if the number of credits is non-negative as the assumption is that this is indicative of migration being complete. This assumption is incorrect as a non-negative number of credits can also be the result of a failed migration. The destruction of a region that still has filters referencing it can result in a use-after-free [1]. Fix by not destroying the region if migration failed. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230 Read of size 8 at addr ffff8881735319e8 by task kworker/0:31/3858 CPU: 0 PID: 3858 Comm: kworker/0:31 Tainted: G W 6.9.0-rc2-custom-00782-gf2275c2157d8 #5 Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019 Workqueue: mlxsw_core mlxsw_sp_acl_tcam_vregion_rehash_work Call Trace: <TASK> dump_stack_lvl+0xc6/0x120 print_report+0xce/0x670 kasan_report+0xd7/0x110 mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230 mlxsw_sp_acl_ctcam_entry_del+0x2e/0x70 mlxsw_sp_acl_atcam_entry_del+0x81/0x210 mlxsw_sp_acl_tcam_vchunk_migrate_all+0x3cd/0xb50 mlxsw_sp_acl_tcam_vregion_rehash_work+0x157/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 174: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 __kmalloc+0x19c/0x360 mlxsw_sp_acl_tcam_region_create+0xdf/0x9c0 mlxsw_sp_acl_tcam_vregion_rehash_work+0x954/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30 Freed by task 7: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 poison_slab_object+0x102/0x170 __kasan_slab_free+0x14/0x30 kfree+0xc1/0x290 mlxsw_sp_acl_tcam_region_destroy+0x272/0x310 mlxsw_sp_acl_tcam_vregion_rehash_work+0x731/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/311eeaa7b9e26aba5b3d57b09859f07d8e9fc049
- git.kernel.org/stable/c/4c89642ca47fb620914780c7c51d8d1248201121
- git.kernel.org/stable/c/54225988889931467a9b55fdbef534079b665519
- git.kernel.org/stable/c/813e2ab753a8f8c243a39ede20c2e0adc15f3887
- git.kernel.org/stable/c/a02687044e124f8ccb427cd3632124a4e1a7d7c1
- git.kernel.org/stable/c/a429a912d6c779807f4d72a6cc0a1efaaa3613e1
- git.kernel.org/stable/c/e118e7ea24d1392878ef85926627c6bc640c4388
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2024/06/msg00017.htmlMailing List, Third Party Advisory
Recent Use After Free vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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