bpf: fix potential 32-bit overflow when accessing ARRAY map element

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: fix potential 32-bit overflow when accessing ARRAY map element If BPF array map is bigger than 4GB, element pointer calculation can overflow because both index and elem_size are u32. Fix this everywhere by forcing 64-bit multiplication. Extract this formula into separate small helper and use it consistently in various places. Speculative-preventing formula utilizing index_mask trick is left as is, but explicit u64 casts are added in both places.

References

• https://git.kernel.org/stable/c/063e092534d4c6785228e5b1eb6e9329f66ccbe4
• https://git.kernel.org/stable/c/3c7256b880b3a5aa1895fd169a34aa4224a11862
• https://git.kernel.org/stable/c/87ac0d600943994444e24382a87aa19acc4cd3d4