CVE-2023-53000: Improper Validation of Array Index

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

netlink: prevent potential spectre v1 gadgets

Most netlink attributes are parsed and validated from __nla_validate_parse() or validate_nla()

u16 type = nla_type(nla);

if (type == 0 || type > maxtype) { /* error or continue */ }

@type is then used as an array index and can be used as a Spectre v1 gadget.

array_index_nospec() can be used to prevent leaking content of kernel memory to malicious users.

This should take care of vast majority of netlink uses, but an audit is needed to take care of others where validation is not yet centralized in core netlink functions.