CVE-2021-46950: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved:

md/raid1: properly indicate failure when ending a failed write request

This patch addresses a data corruption bug in raid1 arrays using bitmaps. Without this fix, the bitmap bits for the failed I/O end up being cleared.

Since we are in the failure leg of raid1_end_write_request, the request either needs to be retried (R1BIO_WriteError) or failed (R1BIO_Degraded).