In the Linux kernel, the following vulnerability has been resolved: net/sched: schfq: fix integer overflow of "credit" if schfq is configured with "initial quantum" having values greater than INTMAX, the first assignment of "credit" does signed integer overflow to a very negative value. In this situation, the syzkaller script provided by Cristoph triggers the CPU soft-lockup warning even with few sockets. It's not an infinite loop, but "credit" wasn't probably meant to be minus 2Gb for each new flow. Capping "initial quantum" to INTMAX proved to fix the issue. v2: validation of "initial quantum" is done in fqpolicy, instead of open coding in fqchange() _ suggested by Jakub Kicinski