CVE-2024-50058

In the Linux kernel, the following vulnerability has been resolved:

serial: protect uart_port_dtr_rts() in uart_shutdown() too

Commit af224ca2df29 (serial: core: Prevent unsafe uart port access, part

3) added few uport == NULL checks. It added one to uart_shutdown(), so

the commit assumes, uport can be NULL in there. But right after that

protection, there is an unprotected "uart_port_dtr_rts(uport, false);"

call. That is invoked only if HUPCL is set, so I assume that is the

reason why we do not see lots of these reports.

Or it cannot be NULL at this point at all for some reason :P.

Until the above is investigated, stay on the safe side and move this

dereference to the if too.

I got this inconsistency from Coverity under CID 1585130. Thanks.