Linux: Use After Free
CVE-2024-35855 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 1b73f6e4ea770410a937a8db98f77e52594d23a0, e24d2487424779c02760ff50cd9021b8676e19ef, c17976b42d546ee118ca300db559630ee96fb758 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 1b73f6e4ea770410a937a8db98f77e52594d23a0 or e24d2487424779c02760ff50cd9021b8676e19ef or c17976b42d546ee118ca300db559630ee96fb758 or b996e8699da810e4c915841d6aaef761007f933a, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.275 or 5.10.216 or 5.15.158 or 6.1.90, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, 1b73f6e4ea770410a937a8db98f77e52594d23a0; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, e24d2487424779c02760ff50cd9021b8676e19ef; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, c17976b42d546ee118ca300db559630ee96fb758; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, b996e8699da810e4c915841d6aaef761007f933a; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, feabdac2057e863d0e140a2adf3d232eb4882db4; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, b183b915beef818a25e3154d719ca015a1ae0770; 2bffc5322fd8679e879cd6370881ee50cf141ada up to, but not including, 79b5b4b18bc85b19d3a518483f9abbbe6d7b3ba4; 5.1 | 1b73f6e4ea770410a937a8db98f77e52594d23a0, e24d2487424779c02760ff50cd9021b8676e19ef, c17976b42d546ee118ca300db559630ee96fb758, b996e8699da810e4c915841d6aaef761007f933a, feabdac2057e863d0e140a2adf3d232eb4882db4, b183b915beef818a25e3154d719ca015a1ae0770 |
| Linux | Linux Kernel | 5.1 up to, but not including, 5.4.275; 5.5 up to, but not including, 5.10.216; 5.11 up to, but not including, 5.15.158; 5.16 up to, but not including, 6.1.90; 6.2 up to, but not including, 6.6.30; 6.7 up to, but not including, 6.8.9; 6.9 | 5.4.275, 5.10.216, 5.15.158, 6.1.90, 6.6.30, 6.8.9 |
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: mlxsw: spectrum_acl_tcam: Fix possible use-after-free during activity update The rule activity update delayed work periodically traverses the list of configured rules and queries their activity from the device. As part of this task it accesses the entry pointed by 'ventry->entry', but this entry can be changed concurrently by the rehash delayed work, leading to a use-after-free [1]. Fix by closing the race and perform the activity query under the 'vregion->lock' mutex. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_acl_tcam_flower_rule_activity_get+0x121/0x140 Read of size 8 at addr ffff8881054ed808 by task kworker/0:18/181 CPU: 0 PID: 181 Comm: kworker/0:18 Not tainted 6.9.0-rc2-custom-00781-gd5ab772d32f7 #2 Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019 Workqueue: mlxsw_core mlxsw_sp_acl_rule_activity_update_work Call Trace: <TASK> dump_stack_lvl+0xc6/0x120 print_report+0xce/0x670 kasan_report+0xd7/0x110 mlxsw_sp_acl_tcam_flower_rule_activity_get+0x121/0x140 mlxsw_sp_acl_rule_activity_update_work+0x219/0x400 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 1039: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 __kmalloc+0x19c/0x360 mlxsw_sp_acl_tcam_entry_create+0x7b/0x1f0 mlxsw_sp_acl_tcam_vchunk_migrate_all+0x30d/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 Freed by task 1039: 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_vchunk_migrate_all+0x3d7/0xb50 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
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
- git.kernel.org/stable/c/1b73f6e4ea770410a937a8db98f77e52594d23a0
- git.kernel.org/stable/c/79b5b4b18bc85b19d3a518483f9abbbe6d7b3ba4
- git.kernel.org/stable/c/b183b915beef818a25e3154d719ca015a1ae0770
- git.kernel.org/stable/c/b996e8699da810e4c915841d6aaef761007f933a
- git.kernel.org/stable/c/c17976b42d546ee118ca300db559630ee96fb758
- git.kernel.org/stable/c/e24d2487424779c02760ff50cd9021b8676e19ef
- git.kernel.org/stable/c/feabdac2057e863d0e140a2adf3d232eb4882db4
- lists.debian.org/debian-lts-announce/2024/06/msg00017.html
Recent Use After Free vulnerabilities
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- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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