CVE-2021-46904 — net: hso: fix null-ptr-deref during tty device unregistration

Affected: Linux

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.

USN-6971-1 — linux vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: linux

It was discovered that the Option USB High Speed Mobile device driver in the Linux kernel did not properly handle error conditions. A physically proximate attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2021-37159)

A security issue was discovered in the Linux kernel. An attacker could possibly use this to compromise the system. This update corrects flaws in the following subsystem: - Network drivers; (CVE-2021-46904)

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CVE-2021-46904 — net: hso: fix null-ptr-deref during tty device unregistration

USN-6971-1 — linux vulnerabilities