Linux Kernel up to 5.11.13 hso get_free_serial_index use after free

Summaryinfo

A vulnerability was found in Linux Kernel up to 5.11.13. It has been classified as critical. Impacted is the function get_free_serial_index of the component hso. Performing a manipulation results in use after free. This vulnerability is identified as CVE-2021-46904. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 5.11.13 (Operating System). This affects the function get_free_serial_index of the component hso. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: net: hso: fix null-ptr-deref during tty device unregistration Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref. The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number. Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call.

The weakness was released 02/25/2024. The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2021-46904 since 02/25/2024. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 247774 (Linux Distros Unpatched Vulnerability : CVE-2021-46904), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.4.268, 4.9.268, 4.14.232, 4.19.187, 5.4.112, 5.10.30, 5.11.14 or 5.12 eliminates this vulnerability. Applying the patch a462067d7c8e/145c89c441d2/caf5ac93b3b5/92028d7a31e5/4a2933c88399/dc195928d7e4/388d05f70f1e/8a12f8836145 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (247774). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.4.267
• 4.9.267
• 4.14.231
• 4.19.186
• 5.0
• 5.1
• 5.2
• 5.3
• 5.4
• 5.4.111
• 5.5
• 5.6
• 5.7
• 5.8
• 5.9
• 5.10
• 5.10.0
• 5.10.1
• 5.10.2
• 5.10.3
• 5.10.4
• 5.10.5
• 5.10.6
• 5.10.7
• 5.10.8
• 5.10.9
• 5.10.10
• 5.10.11
• 5.10.12
• 5.10.13
• 5.10.14
• 5.10.15
• 5.10.16
• 5.10.17
• 5.10.18
• 5.10.19
• 5.10.20
• 5.10.21
• 5.10.22
• 5.10.23
• 5.10.24
• 5.10.25
• 5.10.26
• 5.10.27
• 5.10.28
• 5.10.29
• 5.11
• 5.11.0
• 5.11.1
• 5.11.2
• 5.11.3
• 5.11.4
• 5.11.5
• 5.11.6
• 5.11.7
• 5.11.8
• 5.11.9
• 5.11.10
• 5.11.11
• 5.11.12
• 5.11.13

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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