A flaw was found in the Linux kernel in the RISC-V architecture. The issue arises in the perf subsystem's handling of Performance Monitoring Unit (PMU) overflow interrupts. Specifically, it involves an error when setting bits in the overflowed_ctrs variable, where an incorrect shift operation using an `int` rather than an unsigned long can lead to kernel panic. This vulnerability triggers a NULL pointer dereference, causing the kernel to crash when running certain perf commands, such as perf record -e branches, on systems like the Sophgo SG2042. The issue results in system instability, potentially leading to a denial-of-service (DoS) scenario. The problem has been fixed by replacing the faulty code with a more appropriate bit-setting operation using the BIT() macro.