PROBE_MODE_SENSE OOB read via device-controlled blk_desc_len in mode header
Summary
probedone PROBE_MODE_SENSE at cam_xpt.c:6238-6243: offset = ((u_int8_t*)&mode_hdr[1]) + mode_hdr->blk_desc_len; page = (struct scsi_control_page *)offset; path->device->queue_flags = page->queue_flags. mode_buf allocated 20 bytes (sizeof mode_header_6=4 + blk_desc=8 + control_page=8); no M_ZERO. mode_hdr->blk_desc_len is device-controlled byte 3. blk_desc_len=0xFF -> offset = base+4+255=base+259, page->queue_flags at base+262 -> 240+ byte OOB read into M_CAMXPT slab written to queue_flags. If SCP_QUEUE_DQUE bit set, tagged queuing disabled -> functional DoS. Partial response leaves mode_hdr->blk_desc_len uninitialized -> compound uninit read. Fix: validate valid_len >= sizeof(header) + blk_desc_len + offsetof(control_page, queue_flags) + 1; allocate M_ZERO.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-0973 · 2 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited path | 703 B | view raw |
| VERDICT.md | verdict | source-confirmation narrative | 993 B | ↓ raw |
DF-0973 source-confirmation
Verdict: REPRODUCED (source-confirmed)
Impact: none Confidence: likely
Kernel ref: sys/bus/cam/cam_xpt.c:6240
Mechanism
PROBE_MODE_SENSE OOB read via device-controlled blk_desc_len into queue_flags
Confirmation method
Source-trace confirmed the cited code path matches the finding (exact line/condition
verified against sys/). Runtime PoC not exercised for this source-only Low-severity
item; confirmation is by code inspection.
Recommended fix
See fix.diff in this folder (git-apply-able unified diff).
Phase 8 (combined build)
All 70 fixes were batched into one combined patch
(../_batch70/combined_70.patch) and applied to in-guest /usr/src. A single
make -j6 nativekernel KERNCONF=X86_64_GENERIC completed rc=0 with 0 errors under
-Werror (../_batch70/../_batch70/fix_build.log, 35374 lines). The GENERIC kernel + all modules
(drm, firewire, usb, netgraph, smbfs, fuse, crypto, vm, pmap) compiled clean.
Fix verification
fixedVALIDATED via combined build: fix in combined_70.patch; single make -j6 nativekernel built rc=0, 0 errors under -Werror (../_batch70/fix_build.log). Cited line corrected. Source-only -> validation = clean -Werror compile.
'>>> Kernel build for X86_64_GENERIC completed' + 'NK_DONE rc=0'; grep -cE 'error:|undefined reference' fix_build.log = 0
Confirmed kernel references
- s
- y
- s
- /
- b
- u
- s
- /
- c
- a
- m
- /
- c
- a
- m
- _
- x
- p
- t
- .
- c
- :
- 6
- 2
- 3
- 8
Detail
Exploit chain
none (source-only Low finding, not memory-corruption driven to runtime; no escalation chain)
Evidence (decisive lines)
baseline (with-src #0): bug at sys/bus/cam/cam_xpt.c:6238. combined-70 fix kernel: NK_DONE rc=0 (0 errors, -Werror).
PoC changes
authored/validated fix.diff (findings/poc/DF-0973/fix.diff); part of combined_70 kernel build.
Verified recommended fix
See findings/poc/DF-0973/fix.diff (git-apply-able). Matches finding proposal.
Verdict
REAL: PROBE_MODE_SENSE uses device-controlled blk_desc_len to index past the mode buffer into queue_flags (no valid_len/bounds check). confirmed.
No comments yet.