In the Linux kernel, the following vulnerability has been resolved:
hwmon: (nzxt-smart2) DMA-align output buffer
Sashiko reports:
When send_output_report() calls hid_hw_output_report(), the underlying USB HID core calls usb_interrupt_msg() which maps this buffer directly for DMA.
When the DMA mapping flushes or invalidates the cacheline, it will corrupt the adjacent variables (mutex, update_interval) that were modified concurrently by the CPU. This causes memory corruption due to cacheline sharing on non-coherent CPU architectures (such as ARM or MIPS). The DMA API debugging tool (CONFIG_DMA_API_DEBUG) will trigger runtime warnings for this violation.
Any operation that triggers send_output_report() (like setting a fan speed or updating the interval) causes the USB DMA mapping. On systems with non-coherent caches, this structural bug causes immediate and deterministic memory corruption.
Align the output buffer to ARCH_DMA_MINALIGN to fix the problem.
References
- https://git.kernel.org/stable/c/080bbf42faf77e6489ab30d5114c5f8f6ccbb1b8
- https://git.kernel.org/stable/c/2332d35aaf206c17acf848522817252732596676
- https://git.kernel.org/stable/c/51a76bc1b8e717ee3fc0d84f15ac51490ca5f76f
- https://git.kernel.org/stable/c/6a2dbce5da2d2163a5b684acf68a0e54582ff0fa
- https://git.kernel.org/stable/c/70ad543ce81f368411b6c721265a3b2d7ab4fda4