Linux Kernel Netlink Bounds-Check Vulnerability in Struct nlmsgerr Creation

A vulnerability in the Linux kernel's netlink implementation allowed for improper bounds-checking during the creation of struct nlmsgerr. This issue arose in anticipation of FORTIFY_SOURCE applying bounds-checks on memcpy operations. The vulnerability has been addressed by replacing the __nlmsg_put function with nlmsg_put, and by clarifying the bounds-checking process to manage memcpy operations across a composite flexible array structure. This change prevents a potential runtime warning about field-spanning writes.

Impact

The vulnerability could have led to memory corruption issues by allowing improper handling of data across structured fields, potentially causing field-spanning write errors.