An issue was discovered in fs/xfs/xfs_icache.c in the Linux kernel through 4.17.3. There is a NULL pointer dereference and panic in lookup_slow() on a NULL inode->i_ops pointer when doing pathwalks on a corrupted xfs image. This occurs because of a lack of proper validation that cached inodes are free during allocation.
https://access.redhat.com/errata/RHSA-2019:2029
https://access.redhat.com/errata/RHSA-2019:2043
https://bugzilla.kernel.org/show_bug.cgi?id=199367
https://github.com/torvalds/linux/commit/afca6c5b2595fc44383919fba740c194b0b76aff
Source: MITRE
Published: 2018-07-03
Updated: 2019-08-06
Type: CWE-476
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.5
Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 1.8
Severity: MEDIUM