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.
https://git.kernel.org/stable/c/ee0c5277d4fab920bd31345c49e193ecede9ecef
https://git.kernel.org/stable/c/70e66bdeae4d0f7c8e87762f425b68aedd5e8955
https://git.kernel.org/stable/c/499fef2030fb754c68b1c7cb3a799a3bc1d0d925
https://git.kernel.org/stable/c/3039d8b8692408438a618fac2776b629852663c3