CVE-2025-38407: 
Linux Kernel vulnerability analysis and mitigation

In the Linux kernel, a vulnerability (CVE-2025-38407) was discovered that affects the RISC-V CPU operations when using SBI (Supervisor Binary Interface). The issue was identified on July 25, 2025, and affects systems with NUMA enabled or when using specific boot configurations (NVD).

The vulnerability stems from an issue introduced by commit 6b9f29b81b15 ("riscv: Enable pcpu page first chunk allocator"). When NUMA is enabled or when the system is booted with percpualloc=page, the page percpu allocator places data in the vmalloc area. However, sbihsmhartstart() requires the physical address of sbihartbootdata and incorrectly assumes _pa() would work correctly. This assumption causes newly started harts to access invalid addresses and hang (NVD).

The vulnerability causes system hangs during SMP boot on affected RISC-V systems, particularly impacting NUMA configurations. This has been specifically confirmed to affect Sophgo SG2042 systems and can be reproduced on QEMU virtual machines (NVD).

The vulnerability has been resolved by implementing a static array for bootdata in the kernel image, as struct sbihartbootdata is small enough to be allocated statically. This ensures the data remains in a valid address space (NVD).