__btrfs_free_extent in fs/btrfs/extent-tree.c in the Linux kernel through 5.3.12 calls btrfs_print_leaf in a certain ENOENT case, which allows local users to obtain potentially sensitive information about register values via the dmesg program.
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1775804]
Another party currently has this issue marked as DISPUTED in the NVD database.
The reason that this is disputed is because the 'register' information is no different than any of the other warnings that show backtracer/register information to system logs. See the Mitigation heading for information on how to prevent this on a system.
Its likely that this flaw will not end up being fixed, due to this being expected behavior.
If this behavior is not derirable, it can be mitigated by explicitly setting the kernel parameter to restrict non privileged users with the command:
sudo sysctl -w kernel.dmesg_restrict=1
And to make persistent between systme reboots.
echo 'kernel.dmesg_restrict=1' | sudo tee -a /etc/sysctl.conf