Bad Block recognition in Nand Flash

[Arno Steffens]

The first 2 bytes of OOB of each block contain the marker for Bad blocks. I found, that this is not protected by ECC in my case here - ore better it is used before ECC is applied. Is this because I am using ancient software or is this a known limitation till today? 
In my implementation this bytes will compared with 0xff. A single bit flip and my device is bricked, as the otherwise good block is not used anymore.

Background for this question: In my old uboot and kernel I just found a few function that are linked with bad block handling. So I am not sure I can make it to find all places where there is just a comparison.

Thanks for your attention.
Arno