CVE-2026-23238

A flaw was found in the Linux kernel's romfs filesystem implementation. The romfs_fill_super() function ignores the return value of sb_set_blocksize(). When mounting a romfs filesystem on a device with an incompatible block size (larger than PAGE_SIZE), the mount proceeds with an incorrect block size, eventually triggering a kernel BUG in folio_set_bh() when attempting I/O operations.

This flaw requires the ability to configure a loop device's block size and mount a romfs filesystem on it. While the configuration sequence requires privileged access, once set up, the kernel BUG triggers during normal filesystem operations. Romfs is a read-only filesystem primarily used in embedded systems and initramfs.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent the romfs module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.