DEBIAN-CVE-2026-99136: Race Condition

In the Linux kernel, the following vulnerability has been resolved: dm-crypt: fix a tiny race condition in cryptdecpending cryptdecpending reads io->error before calling atomicdecandtest. Another context, for example cryptendio called from an interrupt, may set io->error and drop its reference between the read and the decrement. cryptdecpending then drops the last reference and completes the bio with the stale status - so a read that failed and was never decrypted, or a write that failed, is reported as successful. The read was placed before the decrement by commit b35f8caa0890 ("dm crypt: wait for endio to complete before destruction"), because that commit freed dmcryptio before calling bioendio. This is no longer the case, dmcryptio lives in the per-bio data now. Read io->error after atomicdecandtest instead. atomicdecandtest is fully ordered, so no additional barrier is needed.