CVE-2024-35987

In the Linux kernel, the following vulnerability has been resolved:

riscv: Fix loading 64-bit NOMMU kernels past the start of RAM

commit 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear

mapping") added logic to allow using RAM below the kernel load address.

However, this does not work for NOMMU, where PAGE_OFFSET is fixed to the

kernel load address. Since that range of memory corresponds to PFNs

below ARCH_PFN_OFFSET, mm initialization runs off the beginning of

mem_map and corrupts adjacent kernel memory. Fix this by restoring the

previous behavior for NOMMU kernels.