# DF-1965 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:440-445`. 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: in dmtd_mod_handler MOD_UNLOAD, _objcache_destroy() runs unconditionally even when dm_target_remove('delay') returns EBUSY. _objcache_destroy sets obj_cache=NULL, but the linker keeps the module loaded (err!=0). The next bio to any still-active delay target allocates from NULL obj_cache → NULL deref.

## Recommended fix
Only call _objcache_destroy() inside the `if (err == 0)` block, so it doesn't run when the target is still in use.

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.