netfilter: nft_set_pipapo: prevent overflow in lookup table allocation

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: prevent overflow in lookup table allocation When calculating the lookup table size, ensure the following multiplication does not overflow: - desc->field_len[] maximum value is U8_MAX multiplied by NFT_PIPAPO_GROUPS_PER_BYTE(f) that can be 2, worst case. - NFT_PIPAPO_BUCKETS(f->bb) is 2^8, worst case. - sizeof(unsigned long), from sizeof(*f->lt), lt in struct nft_pipapo_field. Then, use check_mul_overflow() to multiply by bucket size and then use check_add_overflow() to the alignment for avx2 (if needed). Finally, add lt_size_check_overflow() helper and use it to consolidate this. While at it, replace leftover allocation using the GFP_KERNEL to GFP_KERNEL_ACCOUNT for consistency, in pipapo_resize().