DF-1110

Memory leak of usrbufs array on I2CRDWR copyin-failure path

Summary

I2CRDWR at iic.c:352 allocates usrbufs = kmalloc(sizeof(void*)*d->nmsgs, M_TEMP, M_ZERO|M_WAITOK). If copyin of message array at :353 fails, execution breaks at :355. Function-level cleanup at :385-386 only frees buf - usrbufs never freed. Leaks sizeof(void*)*nmsgs bytes per failed call. Root can pass large nmsgs (100000) with invalid d->msgs pointer to leak ~800KB per ioctl. Repeated in tight loop exhausts kernel malloc memory. Fix: add kfree(usrbufs) to cleanup and null after happy-path free.

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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:H/UI:N/S:U:C:N/I:N/A:L
CWE: CWE-401 Missing Release of Memory after Effective Lifetime
File: sys/bus/iicbus/iic.c
Lines: 352-386
Area: hw
Discovered: 2026-07-15
Updated: 2026-07-15

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: leak
Confidence: certain
Tested: 2026-07-25 10:25:02
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 10:25:02
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1110/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1110 · 3 files

File	Type	Description	Size
VERDICT.md	verdict	Source-confirmation verdict for DF-1110	604 B	↓ raw
fix.diff	suggested-fix	Free usrbufs on copyin failure path	962 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-1110

↓ download raw

DF-1110 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: Free usrbufs on copyin failure path

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): I2CRDWR allocates usrbufs = kmalloc(sizeof(void*)*d->nmsgs); on copyin failure the break skips per-msg free loop, leaking usrbufs and any partially-allocated m->buf entries.

Verified recommended fix

REPRODUCED (source-only): I2CRDWR allocates usrbufs = kmalloc(sizeof(void)d->nmsgs); on copyin failure the break skips per-msg free loop, leaking usrbufs and any partially-allocated m->buf entries.

Verdict

REPRODUCED (source-only): I2CRDWR allocates usrbufs = kmalloc(sizeof(void)d->nmsgs); on copyin failure the break skips per-msg free loop, leaking usrbufs and any partially-allocated m->buf entries.