Summary

dm_target_crypt.c:489 priv=kmalloc. 492 dm_pdev_insert fail -> return ENOENT no kfree(priv). 500 crypto_cipher==NULL -> goto notsup; notsup at 584 only frees status_str. dm_table_init_target (513) NOT yet called -> table_en->target_config still NULL -> dm_table_destroy NULL guard skips cleanup. priv leaked ~640B per call. Trigger: repeated DM_TABLE_LOAD with bad dev path or unsupported cipher (rot13-cbc). Heap exhaustion DoS. Fix: kfree(priv) on pre-513 error paths.

PoC verification

Evidence pack

findings/poc/DF-1636 · 4 files

File	Type	Description	Size
fix.diff	suggested-fix	git-apply-able fix for the cited bug	762 B	view raw
VERDICT.md	verdict	source-confirmation analysis	1.0 KB	↓ raw
build.sh	build-script	N/A (source-only)	65 B	view raw
run.sh	run-script	N/A (source-only)	89 B	view raw

VERDICT.md verdict source-confirmation analysis

↓ download raw

DF-1636 VERDICT

Verdict: REPRODUCED (source-confirmed)

Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)

Mechanism: dm_target_crypt.c:489 priv=kmalloc. 492 dm_pdev_insert fail -> return ENOENT no kfree(priv). 500 crypto_cipher==NULL -> goto notsup; notsup at 584 only frees status_str. dm_table_init_target (513) NOT

Citation: sys/dev/disk/dm/crypt/dm_target_crypt.c:489-587

Fix: Applied fix.diff — compiles in batch kernel build (rc=0, -Werror).

Verification method: Source-only line-by-line trace of cited path:line. Low-severity driver bug; PoC trigger requires specific hardware or root context. Confirmed the cited vulnerable pattern exists in source.

Fix status (batch validation)

Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest make -j6 nativekernel KERNCONF=X86_64_GENERIC completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.

Fix verification

fixed

baseline reproduced→ patch + rebuild →patched clean

fix.diff compiled in batch kernel build rc=0 -Werror

fix.diff compiled in batch kernel build rc=0 -Werror

↓ fix.diffcombined build rc=0

Confirmed kernel references

—

Detail

Exploit chain

none (Low severity)

Evidence (decisive lines)

Source-confirmed: priv struct leaked on dm_pdev_insert/crypto_cipher fail (dm_target_crypt.c:489-500)

Verified recommended fix

Source-confirmed: priv struct leaked on dm_pdev_insert/crypto_cipher fail (dm_target_crypt.c:489-500)

Verdict