CVE-2021-46904

MEDIUM
Published Feb 26, 2024 Modified Nov 21, 2024 CWE-476

Description

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.

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CVSS v3.1 Score

5.5
MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor Product
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel
linux linux_kernel

References

Advisories & Patches

https://git.kernel.org/stable/c/145c89c441d27696961752bf51b323f347601bee https://git.kernel.org/stable/c/388d05f70f1ee0cac4a2068fd295072f1a44152a https://git.kernel.org/stable/c/4a2933c88399c0ebc738db39bbce3ae89786d723 https://git.kernel.org/stable/c/8a12f8836145ffe37e9c8733dce18c22fb668b66 https://git.kernel.org/stable/c/92028d7a31e55d53e41cff679156b9432cffcb36 https://git.kernel.org/stable/c/a462067d7c8e6953a733bf5ade8db947b1bb5449 https://git.kernel.org/stable/c/caf5ac93b3b5d5fac032fc11fbea680e115421b4 https://git.kernel.org/stable/c/dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72ac https://git.kernel.org/stable/c/145c89c441d27696961752bf51b323f347601bee https://git.kernel.org/stable/c/388d05f70f1ee0cac4a2068fd295072f1a44152a https://git.kernel.org/stable/c/4a2933c88399c0ebc738db39bbce3ae89786d723 https://git.kernel.org/stable/c/8a12f8836145ffe37e9c8733dce18c22fb668b66 https://git.kernel.org/stable/c/92028d7a31e55d53e41cff679156b9432cffcb36 https://git.kernel.org/stable/c/a462067d7c8e6953a733bf5ade8db947b1bb5449 https://git.kernel.org/stable/c/caf5ac93b3b5d5fac032fc11fbea680e115421b4 https://git.kernel.org/stable/c/dc195928d7e4ec7b5cfc6cd10dc4c8d87a7c72ac

Frequently Asked Questions

What is CVE-2021-46904? +
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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).
How severe is CVE-2021-46904? +
CVE-2021-46904 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.
What products are affected by CVE-2021-46904? +
CVE-2021-46904 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2021-46904? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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