DF-5129

for_each_sg lacks Linux's `&& sg' termination guard — list shorter than sgmax turns into sg_next(NULL) NULL-deref panic

Summary

DF's macro has no NULL check: a physical list terminating before the caller's sgmax calls sg_next(NULL) -> NULL->flags fatal fault. In-tree callers are consistent today - latent robustness/compat divergence of the same LinuxKPI-contract family as DF-5128. One-line match-Linux fix.

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Severity: Low
Status: new
Bucket: Base system — drivers
Confidence: certain
Pass: 2 · GLM 5.3 second pass
CVSS 3.1: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-476
File: sys/dev/drm/linux_scatterlist.c
Lines: 342-343
Area: dev
Discovered: 2026-09-30
Updated: 2026-09-30

Team triage

untriaged

priority: — · owner: —

PoC verification

untested

Status: untested
Reproduced: no
Impact: NULL-deref panic inside drm code on caller/list count mismatch
Confidence: certain
Tested: 2026-09-30 04:26:30
Attempts: 0
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0: Thu Jul 2 06:02:54 UTC 2026 root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC x86_64
Build cmd: n/a
Run cmd: n/a

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: no
Patched reproduced: no
Confidence: certain
Tested: 2026-09-30 04:26:30
Runtime: —
Kernel: per-fix-DF-5129
fix.diff: findings/poc/DF-5129/fix.diff
Runner: df-bsd-reviewer

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PoC verification

Evidence pack

findings/poc/DF-5129 · 1 files

File	Type	Description	Size
verdict.json	file		1.0 KB	view raw

Fix verification

not_testable

baseline no→ patch + rebuild →patched clean

per-fix-DF-5129

Confirmed kernel references

sys/dev/drm/include/linux/scatterlist.h:342

Detail

Evidence (decisive lines)

source trace in finding markdown

Verified recommended fix

add '&& sg' to the for_each_sg macro (scatterlist.h:342-343)

Verdict

untested (Low, latent/speculative; no in-tree trigger or absent hardware - pack minimal, evidence in finding markdown)