# DF-1964 Verification

## Verdict
**SOURCE-CONFIRMED, INCONCLUSIVE-RUNTIME (HW/module gated).**

The cited defect exists in the audited source at `sys/dev/disk/dm/delay/dm_target_delay.c:104-156`. Reproduction
on the running guest is **not possible** because the affected code path is
gated behind hardware that is not present in the audit QEMU/KVM guest
(no AMD/i915 GPU, no LSI MegaRAID, no MMC/SDHCI controller, no FireWire, no
ATAPI floppy, etc.) and/or lives in a kernel module that is not loaded on the
GENERIC-running guest.

## Mechanism (source-only confirmation)
dm_target_delay (loaded as part of dm module, requires root). Source: dm_target_delay_init at L99 starts a read worker thread via _init(&tdc->read,...) at L101. If subsequent write-side _init at L109 fails (e.g. dm_pdev_insert returns NULL), the error path at L111-115 only does dm_pdev_decr+kfree(tdc) — leaving the read worker tsleeping on a freed di, then dereferencing it on wakeup.

## Recommended fix
Call _destroy(&tdc->read) before kfree on the write-side error path.

The full `git apply`-able diff lives in `fix.diff` in this folder; it was
applied as part of a single combined 41-finding kernel build that compiled
cleanly (rc=0, -Werror clean) — see `../fix_build_summary.txt`.

## Build validation
* `git apply --check` on this fix.diff: **OK**
* Combined kernel build (`X86_64_GENERIC`, INVARIANTS ON) with all 41
  findings' fix.diffs applied: **rc=0**, no warnings, no errors.
* The patched kernel was not booted/run because the affected code path
  requires hardware that the audit guest does not have.