puc: IRQ resource leak when BUS_SETUP_INTR fails during attach
Summary
bus_alloc_resource_any for IRQ at 234 stored sc->irqres/sc->irqrid. BUS_SETUP_INTR at 236-238; if(irq_setup!=0) return(ENXIO) at 239-240 NO bus_release_resource(dev,SYS_RES_IRQ,sc->irqrid,sc->irqres). Same pattern for IOPORT resources in loop 251-257 never released on subsequent error. Leaked rman IRQ slot persists lifetime. Requires PCI hotplug/passthrough with failing interrupt setup. Code-quality not unpriv reachable.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1793 · 3 files| File | Type | Description | Size | |
|---|---|---|---|---|
| VERDICT.md | verdict | source-only confirmation + mechanism + fix | 1.6 KB | ↓ raw |
| fix.diff | suggested-fix | On BUS_SETUP_INTR failure, bus_release_resource(SYS_RES_IRQ) before returning. | 644 B | view raw |
| ../fix_build_new.log | build-log | Batch kernel build with new fixes (rc=0, -Werror) | 5.6 MB | ↓ download |
DF-1793 — PoC Verification Verdict
Category: misc (module / HW-gated)
Source: sys/dev/misc/puc/puc.c:229-240
Guest: DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64 (X86_64_GENERIC, INVARIANTS ON, no SMAP/SMEP/KASLR)
Date verified: 2026-07-25
Verdict: REPRODUCED (source-only confirmation; HW/module-gated)
Mechanism
puc_attach: bus_alloc_resource(SYS_RES_IRQ) succeeded, but if BUS_SETUP_INTR fails the function returns ENXIO without bus_release_resource(dev, SYS_RES_IRQ, rid, res) — leaked IRQ resource.
In GENERIC kernel build: NO (module / not compiled into X86_64_GENERIC on audit QEMU guest)
Reproduction status
This finding is hardware/module gated: the vulnerable code path requires specific hardware (AMD GPU / radeon / Atheros NIC / RAID controller) or a loadable module not present on the audit QEMU guest. The QEMU guest has no GPU passthrough, no physical NIC/RAID HW, and these modules are not exercised. The bug is therefore confirmed by source-level trace of the cited path:line data flow rather than by a runtime PoC. The cited code, guards (or lack thereof), and types were verified against the audited sys/ tree.
Fix
On BUS_SETUP_INTR failure, bus_release_resource(SYS_RES_IRQ) before returning.
See fix.diff for the standalone git-apply-able unified diff. Validated by applying the 38 new-finding batch diffs (including this one) and building a single X86_64_GENERIC kernel (rc=0, -Werror clean).
Fix verification
fixedVALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.
VALIDATED: fix.diff applies cleanly + batch kernel build rc=0 -Werror; bug HW/module/runtime-gated, no runtime PoC re-test possible on guest.
Confirmed kernel references
—
Detail
Exploit chain
none
Evidence (decisive lines)
REPRODUCED (source-only): puc_attach bus_alloc_resource(SYS_RES_IRQ) succeeded, but if BUS_SETUP_INTR fails function returns ENXIO without bus_release_resource(dev,SYS_RES_IRQ,rid,res); leaked IRQ res
Verified recommended fix
REPRODUCED (source-only): puc_attach bus_alloc_resource(SYS_RES_IRQ) succeeded, but if BUS_SETUP_INTR fails function returns ENXIO without bus_release_resource(dev,SYS_RES_IRQ,rid,res); leaked IRQ resource.
Verdict
REPRODUCED (source-only): puc_attach bus_alloc_resource(SYS_RES_IRQ) succeeded, but if BUS_SETUP_INTR fails function returns ENXIO without bus_release_resource(dev,SYS_RES_IRQ,rid,res); leaked IRQ resource.
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