Affected: Linux

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

mm/damon/sysfs-schemes: put stats for scheme_add_dirs() internal error

damon_sysfs_scheme_add_dirs() setup the tried_regions directory after the stats directory setup is completed. When the tried_regions directory setup is failed, the setup function ensures the reference for the tried regions directory is released. Hence the error path should put references on setup succeeded directory objects, starting from the stats directory. However, the error path is putting the tried_regions directory instead of the stats directory.

As a direct result, the stats directory object is leaked. Worse yet, if the tried_regions directory setup failed from the initial allocation, the scheme->tried_regions field remains uninitialized. The following kobject_put(&scheme->tried_regions->kobj) call in the error path will dereference the uninitialized memory. The setup failures should not be common. But once it happens, the consequence is quite bad.

Fix this issue by correctly putting the stats directory instead of the tried_regions directory.

The issue was discovered [1] by Sashiko.