CVE-2021-46945

In the Linux kernel, the following vulnerability has been resolved: ext4:
always panic when errors=panic is specified Before commit 014c9caa29d3
(“ext4: make ext4_abort() use __ext4_error()”), the following series of
commands would trigger a panic: 1. mount /dev/sda -o ro,errors=panic test
2. mount /dev/sda -o remount,abort test After commit 014c9caa29d3,
remounting a file system using the test mount option “abort” will no longer
trigger a panic. This commit will restore the behaviour immediately before
commit 014c9caa29d3. (However, note that the Linux kernel’s behavior has
not been consistent; some previous kernel versions, including 5.4 and 4.19
similarly did not panic after using the mount option “abort”.) This also
makes a change to long-standing behaviour; namely, the following series
commands will now cause a panic, when previously it did not: 1. mount
/dev/sda -o ro,errors=panic test 2. echo test >
/sys/fs/ext4/sda/trigger_fs_error However, this makes ext4’s behaviour much
more consistent, so this is a good thing.