Linux: Use After Free
CVE-2024-42271 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 84f40b46787ecb67c7ad08a5bb1376141fa10c01, 37652fbef9809411cea55ea5fa1a170e299efcd0, c65f72eec60a34ace031426e04e9aff8e5f04895 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 0.24% 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 84f40b46787ecb67c7ad08a5bb1376141fa10c01 or 37652fbef9809411cea55ea5fa1a170e299efcd0 or c65f72eec60a34ace031426e04e9aff8e5f04895 or ac758e1f663fe9bc64f6b47212a2aa18697524f5, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.19.320 or 5.4.282 or 5.10.224 or 5.15.165, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, 84f40b46787ecb67c7ad08a5bb1376141fa10c01; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, 37652fbef9809411cea55ea5fa1a170e299efcd0; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, c65f72eec60a34ace031426e04e9aff8e5f04895; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, ac758e1f663fe9bc64f6b47212a2aa18697524f5; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, 8b424c9e44111c5a76f41c6b741f8d4c4179d876; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, 01437282fd3904810603f3dc98d2cac6b8b6fc84; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, 69620522c48ce8215e5eb55ffbab8cafee8f407d; 7d316b9453523498246e9e19a659c423d4c5081e up to, but not including, f558120cd709682b739207b48cf7479fd9568431; and 1 more ranges | 84f40b46787ecb67c7ad08a5bb1376141fa10c01, 37652fbef9809411cea55ea5fa1a170e299efcd0, c65f72eec60a34ace031426e04e9aff8e5f04895, ac758e1f663fe9bc64f6b47212a2aa18697524f5, 8b424c9e44111c5a76f41c6b741f8d4c4179d876, 01437282fd3904810603f3dc98d2cac6b8b6fc84 |
| Linux | Linux Kernel | 3.4 up to, but not including, 4.19.320; 4.20 up to, but not including, 5.4.282; 5.5 up to, but not including, 5.10.224; 5.11 up to, but not including, 5.15.165; 5.16 up to, but not including, 6.1.104; 6.2 up to, but not including, 6.6.45; 6.7 up to, but not including, 6.10.4; 6.11 | 4.19.320, 5.4.282, 5.10.224, 5.15.165, 6.1.104, 6.6.45 |
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: net/iucv: fix use after free in iucv_sock_close() iucv_sever_path() is called from process context and from bh context. iucv->path is used as indicator whether somebody else is taking care of severing the path (or it is already removed / never existed). This needs to be done with atomic compare and swap, otherwise there is a small window where iucv_sock_close() will try to work with a path that has already been severed and freed by iucv_callback_connrej() called by iucv_tasklet_fn(). Example: [452744.123844] Call Trace: [452744.123845] ([<0000001e87f03880>] 0x1e87f03880) [452744.123966] [<00000000d593001e>] iucv_path_sever+0x96/0x138 [452744.124330] [<000003ff801ddbca>] iucv_sever_path+0xc2/0xd0 [af_iucv] [452744.124336] [<000003ff801e01b6>] iucv_sock_close+0xa6/0x310 [af_iucv] [452744.124341] [<000003ff801e08cc>] iucv_sock_release+0x3c/0xd0 [af_iucv] [452744.124345] [<00000000d574794e>] __sock_release+0x5e/0xe8 [452744.124815] [<00000000d5747a0c>] sock_close+0x34/0x48 [452744.124820] [<00000000d5421642>] __fput+0xba/0x268 [452744.124826] [<00000000d51b382c>] task_work_run+0xbc/0xf0 [452744.124832] [<00000000d5145710>] do_notify_resume+0x88/0x90 [452744.124841] [<00000000d5978096>] system_call+0xe2/0x2c8 [452744.125319] Last Breaking-Event-Address: [452744.125321] [<00000000d5930018>] iucv_path_sever+0x90/0x138 [452744.125324] [452744.125325] Kernel panic - not syncing: Fatal exception in interrupt Note that bh_lock_sock() is not serializing the tasklet context against process context, because the check for sock_owned_by_user() and corresponding handling is missing. Ideas for a future clean-up patch: A) Correct usage of bh_lock_sock() in tasklet context, as described in Re-enqueue, if needed. This may require adding return values to the tasklet functions and thus changes to all users of iucv. B) Change iucv tasklet into worker and use only lock_sock() in af_iucv.
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/01437282fd3904810603f3dc98d2cac6b8b6fc84
- git.kernel.org/stable/c/37652fbef9809411cea55ea5fa1a170e299efcd0
- git.kernel.org/stable/c/69620522c48ce8215e5eb55ffbab8cafee8f407d
- git.kernel.org/stable/c/84f40b46787ecb67c7ad08a5bb1376141fa10c01
- git.kernel.org/stable/c/8b424c9e44111c5a76f41c6b741f8d4c4179d876
- git.kernel.org/stable/c/ac758e1f663fe9bc64f6b47212a2aa18697524f5
- git.kernel.org/stable/c/c65f72eec60a34ace031426e04e9aff8e5f04895
- git.kernel.org/stable/c/f558120cd709682b739207b48cf7479fd9568431
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Spotted an error? Tell us.