Linux: Double Free
CVE-2024-49983 is a high-severity double 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 8c26d9e53e5fbacda0732a577e97c5a5b7882aaf, a34bed978364114390162c27e50fca50791c568d, 6367d3f04c69e2b8770b8137bd800e0784b0abbc 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 0.25% 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 8c26d9e53e5fbacda0732a577e97c5a5b7882aaf or a34bed978364114390162c27e50fca50791c568d or 6367d3f04c69e2b8770b8137bd800e0784b0abbc or 1b558006d98b7b0b730027be0ee98973dd10ee0d, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.227 or 5.15.168 or 6.1.113 or 6.6.55, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 8c26d9e53e5fbacda0732a577e97c5a5b7882aaf; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, a34bed978364114390162c27e50fca50791c568d; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 6367d3f04c69e2b8770b8137bd800e0784b0abbc; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 1b558006d98b7b0b730027be0ee98973dd10ee0d; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 3ff710662e8d86a63a39b334e9ca0cb10e5c14b0; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 63adc9016917e6970fb0104ee5fd6770f02b2d80; 8016e29f4362e285f0f7e38fadc61a5b7bdfdfa2 up to, but not including, 5c0f4cc84d3a601c99bc5e6e6eb1cbda542cce95; 5.10 | 8c26d9e53e5fbacda0732a577e97c5a5b7882aaf, a34bed978364114390162c27e50fca50791c568d, 6367d3f04c69e2b8770b8137bd800e0784b0abbc, 1b558006d98b7b0b730027be0ee98973dd10ee0d, 3ff710662e8d86a63a39b334e9ca0cb10e5c14b0, 63adc9016917e6970fb0104ee5fd6770f02b2d80 |
| Linux | Linux Kernel | 5.10 up to, but not including, 5.10.227; 5.11 up to, but not including, 5.15.168; 5.16 up to, but not including, 6.1.113; 6.2 up to, but not including, 6.6.55; 6.7 up to, but not including, 6.10.14; 6.11 up to, but not including, 6.11.3 | 5.10.227, 5.15.168, 6.1.113, 6.6.55, 6.10.14, 6.11.3 |
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: ext4: drop ppath from ext4_ext_replay_update_ex() to avoid double-free When calling ext4_force_split_extent_at() in ext4_ext_replay_update_ex(), the 'ppath' is updated but it is the 'path' that is freed, thus potentially triggering a double-free in the following process: ext4_ext_replay_update_ex ppath = path ext4_force_split_extent_at(&ppath) ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path) ---> path First freed *orig_path = path = NULL ---> null ppath kfree(path) ---> path double-free !!! So drop the unnecessary ppath and use path directly to avoid this problem. And use ext4_find_extent() directly to update path, avoiding unnecessary memory allocation and freeing. Also, propagate the error returned by ext4_find_extent() instead of using strange error codes.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
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/1b558006d98b7b0b730027be0ee98973dd10ee0d
- git.kernel.org/stable/c/3ff710662e8d86a63a39b334e9ca0cb10e5c14b0
- git.kernel.org/stable/c/5c0f4cc84d3a601c99bc5e6e6eb1cbda542cce95
- git.kernel.org/stable/c/6367d3f04c69e2b8770b8137bd800e0784b0abbc
- git.kernel.org/stable/c/63adc9016917e6970fb0104ee5fd6770f02b2d80
- git.kernel.org/stable/c/8c26d9e53e5fbacda0732a577e97c5a5b7882aaf
- git.kernel.org/stable/c/a34bed978364114390162c27e50fca50791c568d
Other references
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
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