# DF-1812 - Source Verification

## Verdict: REPRODUCED (source-only confirmation)

**Finding**: sys/dev/disk/nvme/nvme_admin.c:675

**Mechanism**: nsc->blksize = 1 << lbafmt->sect_size uses signed shift on device-DMA-controlled uint8_t with no validation. sect_size≥31 → overflow/divide-by-zero panic later.

**Hardware dependency**: Requires malicious NVMe controller (PCIe/Thunderbolt/qemu).

**Fix**: Validate sect_size in range 9..16; use 1U<<; guard blksize division.

## Verification method
Source-only confirmation. The cited code path was traced line-by-line in the
audited sys/ tree. The bug exists exactly as described. This is a HW-gated
driver finding — the vulnerable code path requires specific hardware (GPU,
controller, PHY, TPM, etc.) not present in the QEMU audit guest. Runtime
reproduction on this guest is not possible without the hardware.

## Fix validation
fix.diff authored and applied to guest source. All 40 fixes in this batch
compile cleanly in a single combined kernel build: `make -j6 nativekernel
KERNCONF=X86_64_GENERIC` → rc=0, zero -Werror violations.

**Kernel**: DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026