sysctl: Fix out of bounds access for empty sysctl registers

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: sysctl: Fix out of bounds access for empty sysctl registers When registering tables to the sysctl subsystem there is a check to see if header is a permanently empty directory (used for mounts). This check evaluates the first element of the ctl_table. This results in an out of bounds evaluation when registering empty directories. The function register_sysctl_mount_point now passes a ctl_table of size 1 instead of size 0. It now relies solely on the type to identify a permanently empty register. Make sure that the ctl_table has at least one element before testing for permanent emptiness.

References

• https://git.kernel.org/stable/c/15893975e9e382f8294ea8d926f08dc2d8d39ede
• https://git.kernel.org/stable/c/2ae7081bc10123b187e36a4f3a8e53768de31489
• https://git.kernel.org/stable/c/315552310c7de92baea4e570967066569937a843