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

afs: Fix dynamic root getattr

The recent patch to make afs_getattr consult the server didn't account
for the pseudo-inodes employed by the dynamic root-type afs superblock
not having a volume or a server to access, and thus an oops occurs if
such a directory is stat'd.

Fix this by checking to see if the vnode->volume pointer actually points
anywhere before following it in afs_getattr().

This can be tested by stat'ing a directory in /afs.  It may be
sufficient just to do "ls /afs" and the oops looks something like:

        BUG: kernel NULL pointer dereference, address: 0000000000000020
        ...
        RIP: 0010:afs_getattr+0x8b/0x14b
        ...
        Call Trace:
         <TASK>
         vfs_statx+0x79/0xf5
         vfs_fstatat+0x49/0x62

https://git.kernel.org/stable/c/2b2bba96526f25f2eba74ecadb031de2e05a83ce

https://git.kernel.org/stable/c/65c24caf1b9f5b08397c6e805ec24ebc390c6e4d

https://git.kernel.org/stable/c/7844ceada44eca740d31beb3d97b8511b1ca0a9b

https://git.kernel.org/stable/c/7b564e3254b7db5fbfbf11a824627a6c31b932b4

https://git.kernel.org/stable/c/cb78d1b5efffe4cf97e16766329dd7358aed3deb

https://git.kernel.org/stable/c/e3a232e5767051483ffad4cef7d0a89d292a192b