ima: Fix use-after-free on a dentry's dname.name

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: ima: Fix use-after-free on a dentry's dname.name ->d_name.name can change on rename and the earlier value can be freed; there are conditions sufficient to stabilize it (->d_lock on dentry, ->d_lock on its parent, ->i_rwsem exclusive on the parent's inode, rename_lock), but none of those are met at any of the sites. Take a stable snapshot of the name instead.

References

• https://git.kernel.org/stable/c/480afcbeb7aaaa22677d3dd48ec590b441eaac1a
• https://git.kernel.org/stable/c/edf287bc610b18d7a9c0c0c1cb2e97b9348c71bb
• https://git.kernel.org/stable/c/0b31e28fbd773aefb6164687e0767319b8199829
• https://git.kernel.org/stable/c/7fb374981e31c193b1152ed8d3b0a95b671330d4
• https://git.kernel.org/stable/c/dd431c3ac1fc34a9268580dd59ad3e3c76b32a8c
• https://git.kernel.org/stable/c/a78a6f0da57d058e2009e9958fdcef66f165208c
• https://git.kernel.org/stable/c/be84f32bb2c981ca670922e047cdde1488b233de