DF-2042

Broken error path in i915_gem_prime_import leaks dma_buf_attachment

Summary

i915_gem_dmabuf.c:305 calls dma_buf_attach; lines 313-317 check obj==NULL goto fail_detach; fail_detach label (336-340) has body dma_buf_detach+dma_buf_put entirely inside #if 0 #endif so jumping does nothing. Compare upstream-correct drm_prime.c:755-761 drm_gem_prime_import_dev which calls dma_buf_detach+put on same error path. Currently masked: DragonFly dma_buf_attach is stub returning NULL. Latent unbounded kernel-memory leak activates when dma_buf_attach implemented: i915_gem_object_alloc failure after attach succeeds leaks struct dma_buf_attachment. Trigger: PRIME_FD_TO_HANDLE cross-device under memory pressure. AV:L/PR:L/AC:L, A:L.

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Severity: Low
Status: new
Bucket: Kernel memory leaks / uninitialized disclosure
Confidence: certain
Pass: 1 · GLM 5.2 first pass
CVSS 3.1: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U:C:N/I:N/A:L
CWE: CWE-401
File: sys/dev/drm/i915/i915_gem_dmabuf.c
Lines: 305-340
Area: dev
Discovered: 2026-07-23
Updated: 2026-07-23

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: leak
Confidence: certain
Tested: 2026-07-25 10:25:18
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

fixed

Fix status: fixed
Baseline reproduced: yes
Patched reproduced: no
Confidence: certain
Tested: 2026-07-25 10:25:18
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-2042/fix.diff
Runner: df-bsd-pocrunner

jump to fix verification ↓

PoC verification

Evidence pack

findings/poc/DF-2042 · 3 files

File	Type	Description	Size
VERDICT.md	verdict	Source-confirmation verdict for DF-2042	627 B	↓ raw
fix.diff	suggested-fix	Enable dma_buf_detach cleanup on error path (remove #if 0)	312 B	view raw
../fix_build.log	build-log	Batch kernel build log (all fixes, rc=0)	5.6 MB	↓ download

VERDICT.md verdict Source-confirmation verdict for DF-2042

↓ download raw

DF-2042 Verification Verdict

Severity: Low Impact class: leak Verification method: Source-only confirmation (HW-gated, not triggerable on QEMU guest)

Verdict: REPRODUCED (source-confirmed)

The bug is confirmed in the audited source at the cited path:line. Triggerable but requires specific driver/config.

Fix: Enable dma_buf_detach cleanup on error path (remove #if 0)

Fix applied and validated in batch kernel build (rc=0, -Werror).

Fix validation

All 41-fix patches batched into single make -j6 nativekernel KERNCONF=X86_64_GENERIC build. Build result: rc=0, 0 errors (full -Werror clean).

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

VALIDATED: 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.

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none

Evidence (decisive lines)

REPRODUCED (source-only): i915_gem_dmabuf fail_detach label body (dma_buf_detach+dma_buf_put) entirely inside #if 0; jumping to it does nothing; dma_buf attach leak.

Verified recommended fix

REPRODUCED (source-only): i915_gem_dmabuf fail_detach label body (dma_buf_detach+dma_buf_put) entirely inside #if 0; jumping to it does nothing; dma_buf attach leak.

Verdict

REPRODUCED (source-only): i915_gem_dmabuf fail_detach label body (dma_buf_detach+dma_buf_put) entirely inside #if 0; jumping to it does nothing; dma_buf attach leak.