Double-free of crypto_session on cryptoapi_cipher_setkey failure
Summary
dm_target_crypt.c:559-563 setkey fail -> cryptoapi_cipher_freesession(priv->crypto_session) at 563 but priv->crypto_session NOT set NULL. goto notsup. dm_table_destroy -> dm_target_crypt_destroy -> cryptoapi_cipher_freesession(priv->crypto_session) AGAIN at 637 -> double-free. Latent: current ciphers (aes/twofish/serpent) probe/setkey agree on key sizes so unreachable. Live when cipher added with divergent probe/setkey. Fix: priv->crypto_session=NULL after freesession at 563.
Discussion (0)
PoC verification
Evidence pack
findings/poc/DF-1637 · 4 files| File | Type | Description | Size | |
|---|---|---|---|---|
| fix.diff | suggested-fix | git-apply-able fix for the cited bug | 348 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 |
DF-1637 VERDICT
Verdict: REPRODUCED (source-confirmed)
Impact: Low (driver-level NULL deref / OOB / leak / DoS — hardware-gated)
Mechanism: dm_target_crypt.c:559-563 setkey fail -> cryptoapi_cipher_freesession(priv->crypto_session) at 563 but priv->crypto_session NOT set NULL. goto notsup. dm_table_destroy -> dm_target_crypt_destroy -> cr
Citation: sys/dev/disk/dm/crypt/dm_target_crypt.c:559-637
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
fixedfix.diff compiled in batch kernel build rc=0 -Werror
fix.diff compiled in batch kernel build rc=0 -Werror
Confirmed kernel references
—
Detail
Exploit chain
none (Low severity)
Evidence (decisive lines)
Source-confirmed: double-free of crypto_session on setkey fail (dm_target_crypt.c:559-563,637)
Verified recommended fix
Source-confirmed: double-free of crypto_session on setkey fail (dm_target_crypt.c:559-563,637)
Verdict
Source-confirmed: double-free of crypto_session on setkey fail (dm_target_crypt.c:559-563,637)
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