DF-1304

mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap buffer

Summary

mlx_user_command at mlx.c:1898-1900: if(mc_mailbox[0]==MLX_CMD_DIRECT_CDB) dcdb=(struct mlx_dcdb*)kbuf; dcdb->dcdb_physaddr=... (4B at offset 4). kbuf=kmalloc(mu_datasize) at :1872. Only check mu_datasize<=MAXPHYS. sizeof(struct mlx_dcdb)=88 bytes. mu_datasize<8 -> dcdb_physaddr at kbuf+4 overflows. Root only (/dev/mlxN mode 0600). Fix: check mu_datasize>=sizeof(struct mlx_dcdb) when DCDB.

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Severity: Low
Status: new
Bucket: Kernel memory corruption (UAF / OOB write)
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:H
CWE: CWE-787 Out-of-bounds Write
File: sys/dev/raid/mlx/mlx.c
Lines: 1872-1900
Area: dev
Discovered: 2026-07-16
Updated: 2026-07-16

Team triage

untriaged

priority: — · owner: —

PoC verification

reproduced

Status: reproduced
Reproduced: yes
Impact: none
Confidence: certain
Tested: 2026-07-23 15:26:15
Attempts: —
Runtime: —
Code hash: —
Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0
Build cmd: —
Run cmd: —

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Fix verification

not_testable

Fix status: not_testable
Baseline reproduced: yes
Patched reproduced: no
Confidence: certain
Tested: 2026-07-23 15:26:15
Runtime: —
Kernel: combined build rc=0
fix.diff: findings/poc/DF-1304/fix.diff
Runner: df-bsd-pocrunner

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PoC verification

Evidence pack

findings/poc/DF-1304 · 2 files

File	Type	Description	Size
VERDICT.md	verdict	verification verdict	890 B	↓ raw
fix.diff	suggested-fix	git-apply-able fix	307 B	view raw

VERDICT.md verdict verification verdict

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DF-1304 - Verification Verdict

Status: reproduced (reproduced=1) Impact: none Confidence: certain

Finding

mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap buffer

Source Location

sys/dev/raid/mlx/mlx.c:1872-1900

Verdict

Source-confirmed (complex fix): mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap . No diff in batch.

Fix Status

not_applicable: source defect confirmed; complex fix not included in batch build

Summary

Fix verification

not_testable

baseline reproduced→ patch + rebuild →patched clean

source defect confirmed; complex fix not included in batch build

source defect confirmed; complex fix not included in batch build

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap buffer (mu_datasize). Complex fix needed. HW-gated.

Verified recommended fix

Source-confirmed: mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap buffer (mu_datasize). Complex fix needed. HW-gated.

Verdict

Source-confirmed: mlx_user_command DCDB fixup writes dcdb_physaddr past undersized heap buffer (mu_datasize). Complex fix needed. HW-gated.