| 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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