I booted amd64-generic-asan image and browsed to (though ssh) /var/log/asan and found this error in frecon

/mnt/host/source/src/platform/frecon/image.c:60:14: runtime error: left shift of 255 by 24 places cannot be represented in type 'int'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /mnt/host/source/src/platform/frecon/image.c:60:14


To repro:
Download the qemu image from one of the amd64-generic-asan builder artifacts at https://cros-goldeneye.corp.google.com/chromeos/legoland/builderHistory?buildConfig=amd64-generic-asan&buildBranch=master

Boot it via cros_vm.  Start vnc and browse as guest .
In parallel, do ssh to the VM in the chroot and go to /var/log/asan/.
One of the asan log files has error messages about frecon.