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.

• linux linux kernel (>= 2.6.27 < 4.4.268) • linux linux kernel (>= 4.5.0 < 4.9.268) • linux linux kernel (>= 4.10.0 < 4.14.232) • linux linux kernel (>= 4.15.0 < 4.19.187) • linux linux kernel (>= 4.20.0 < 5.4.112) • linux linux kernel (>= 5.5.0 < 5.10.30) • linux linux kernel (>= 5.11.0 < 5.11.14)