CVE-2022-49688 Information

Description

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

Reference

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