CVE-2025-21832: Undefined Security Weakness

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

block: don't revert iter for -EIOCBQUEUED

blkdev_read_iter() has a few odd checks, like gating the position and count adjustment on whether or not the result is bigger-than-or-equal to zero (where bigger than makes more sense), and not checking the return value of blkdev_direct_IO() before doing an iov_iter_revert(). The latter can lead to attempting to revert with a negative value, which when passed to iov_iter_revert() as an unsigned value will lead to throwing a WARN_ON() because unroll is bigger than MAX_RW_COUNT.

Be sane and don't revert for -EIOCBQUEUED, like what is done in other spots.