mm: vmalloc: check if a hash-index is in cpu_possible_mask

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: mm: vmalloc: check if a hash-index is in cpu_possible_mask The problem is that there are systems where cpu_possible_mask has gaps between set CPUs, for example SPARC. In this scenario addr_to_vb_xa() hash function can return an index which accesses to not-possible and not setup CPU area using per_cpu() macro. This results in an oops on SPARC. A per-cpu vmap_block_queue is also used as hash table, incorrectly assuming the cpu_possible_mask has no gaps. Fix it by adjusting an index to a next possible CPU.

References

• https://git.kernel.org/stable/c/28acd531c9a365dac01b32e6bc54aed8c1429bcb
• https://git.kernel.org/stable/c/47f9b6e49b422392fb0e348a65eb925103ba1882
• https://git.kernel.org/stable/c/a34acf30b19bc4ee3ba2f1082756ea2604c19138