UBUNTU-CVE-2021-46945

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UBUNTU-CVE-2021-46945

Summary:

Details: 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.

References: https://ubuntu.com/security/CVE-2021-46945, https://git.kernel.org/linus/ac2f7ca51b0929461ea49918f27c11b680f28995, https://git.kernel.org/stable/c/64e1eebe2131183174f4fbb6b1491355f96c6cde, https://git.kernel.org/stable/c/1e9ea8f4637026b8e965128953f2da061ccae9c4, https://git.kernel.org/stable/c/ac2f7ca51b0929461ea49918f27c11b680f28995, https://www.cve.org/CVERecord?id=CVE-2021-46945