CVE-2023-53091

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

ext4: update s_journal_inum if it changes after journal replay

When mounting a crafted ext4 image, s_journal_inum may change after journal replay, which is obviously unreasonable because we have successfully loaded and replayed the journal through the old s_journal_inum. And the new s_journal_inum bypasses some of the checks in ext4_get_journal(), which may trigger a null pointer dereference problem. So if s_journal_inum changes after the journal replay, we ignore the change, and rewrite the current journal_inum to the superblock.

This issue can only be triggered by mounting a maliciously crafted ext4 image with an inconsistent journal state that causes s_journal_inum to change after replay, potentially bypassing integrity checks and leading to a NULL pointer dereference. Since triggering this condition requires CAP_SYS_ADMIN privileges to mount a crafted filesystem image, the attack vector assumes high privileges.

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.