In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in __close_file_table_ids()
A ksmbd_file can remain alive after logical close while another session
holds a temporary reference obtained through ksmbd_lookup_fd_inode().
ksmbd_close_fd() currently marks the file closed and drops the idr-owned
reference, but leaves the pointer published in the closing session’s idr
until the final reference is dropped.
If the foreign holder performs the final ksmbd_fd_put(), __put_fd_final()
supplies the foreign session’s file table to __ksmbd_close_fd(). The object
is then freed without being removed from its owner’s idr, and the owner
session later dereferences the stale pointer during file-table teardown.
Remove the volatile id from the owner’s idr while ksmbd_close_fd() still
holds that table’s lock, and clear volatile_id before dropping
the idr-owned reference. A later foreign final put then only performs
physical destruction and cannot remove the object from the wrong table.
