net: sched: sch_multiq: fix possible OOB write in multiq_tune()

Open Source Vulnerabilities ASB-A-349777785

In multiq_tune of sch_multiq.c, there is a possible out of bounds write due to a logic error in the code. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

Open Source Vulnerabilities CVE-2024-36978

In the Linux kernel, the following vulnerability has been resolved: net: sched: sch_multiq: fix possible OOB write in multiq_tune() q->bands will be assigned to qopt->bands to execute subsequent code logic after kmalloc. So the old q->bands should not be used in kmalloc. Otherwise, an out-of-bounds write will occur.