# DF-2372 VERDICT

**Status:** reproduced (reproduced)
**Impact:** corruption
**Confidence:** certain
**Attempts:** 2

AcpiOsReadPciConfiguration Width=32 masked every 32-bit PCI config read to zero on the live kernel: raw pci_cfgregread(0:0.0, reg 0, 4) = 0x12378086 while the ACPI path returned 0x00000000 (Width=16 intact at 0x8086). Root cause confirmed at OsdHardware.c:106: (1 << (bytes*8)) - 1 with bytes==4 is the UB shift 1<<32, emitted by clang as a 5-bit-masked shl yielding (1<<0)-1 == 0. Fixed kernel (fix.diff: 64-bit mask) returns the real 0x12378086 at Width=32.

## Kernel references
- `sys/dev/acpica/Osd/OsdHardware.c:96`
- `sys/dev/acpica/Osd/OsdHardware.c:104`
- `sys/dev/acpica/Osd/OsdHardware.c:106`

## Guest
DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #7: Sat Oct 24 00:08:04 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/ACHARNESS  x86_64

## Fix validation
See fix.diff and README.md for the baseline/fixed A/B outputs (run.log / fixed.log).

## Fix status (batch validation)
Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest `make -j6 nativekernel KERNCONF=X86_64_GENERIC` completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.