⬢ DragonFlyBSD Kernel Audit
DF-3776 / manifest.json
← back to finding ↓ download raw 
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
{
  "finding_id": "DF-3776",
  "file": "sys/dev/netif/jme/if_jme.c",
  "verdict": "inconclusive",
  "impact_class": "none",
  "reproduce": {
    "build": "scp findings/poc/DF-3776/{Makefile,jme_callout_replica.c} dfbsd:/root/kmod/ ; vm.sh run_root 'cd /root/kmod && make'",
    "run": "vm.sh run_root 'kldload /root/kmod/jme_callout_replica.ko; sysctl kern.jmereplica.arm=1; sleep 2; sysctl kern.jmereplica.stop_try=1; (sysctl kern.jmereplica.stop_blk=1 >/dev/null 2>&1 &); sleep 6; dmesg | grep \"jmereplica[blk]\" | tail -2; ps -o pid,stat,wchan,command -ax | grep stop_blk | grep -v grep'",
    "expected": "Mechanism PROVEN on the guest kernel by deterministic replica of if_jme.c's exact callout/serializer protocol; jme-specific runtime hardware-gated (inconclusive per family convention). jme_tick (sys/dev/netif/jme/if_jme.c:2566-2582) is a CPU0-pinned MP callout whose callback BLOCKS in lwkt_serialize_enter (&sc->jme_serialize, :2571) and self re-arms at hz (:2579); jme_stop (:2907) and jme_miibus_statchg (:409) tear it down with the synchronous callout_stop() while holding ALL driver serializers (ASSERT_IFNET_SERIALIZED_ALL :2898). DragonFly callout_stop waits for an in-progress callback (sys/kern/kern_timeout.c:1091 -> _callout_cancel_or_stop sync=1, ssleep 'costp' :920). A parked tick therefore deadlocks against the stopper (AB-BA): both threads wedge permanently (sysctl thread D-state wchan 'costp'), the driver serializers are never released, and the CPU0 softclock stops delivering ALL callouts. Replica on the guest: stop under the full serializer array with the jme_tick-shaped handler parked -> callout_stop NEVER returned; fix-shape control (try-enter + 1-tick retry) -> callout_stop returned, pending=0."
  },
  "kernel_refs": [
    "sys/dev/netif/jme/if_jme.c:772",
    "sys/dev/netif/jme/if_jme.c:2571",
    "sys/dev/netif/jme/if_jme.c:2579",
    "sys/dev/netif/jme/if_jme.c:2881",
    "sys/dev/netif/jme/if_jme.c:2898",
    "sys/dev/netif/jme/if_jme.c:2907",
    "sys/dev/netif/jme/if_jme.c:409",
    "sys/dev/netif/jme/if_jme.c:1092",
    "sys/dev/netif/jme/if_jme.c:1589",
    "sys/dev/netif/jme/if_jme.c:1913",
    "sys/dev/netif/jme/if_jme.c:2672",
    "sys/kern/kern_timeout.c:1091",
    "sys/kern/kern_timeout.c:920",
    "sys/kern/kern_timeout.c:423"
  ],
  "artifacts": [
    "README.md",
    "VERDICT.md",
    "jme_callout_replica.c",
    "Makefile",
    "build.sh",
    "run.sh",
    "build.log",
    "run.log",
    "run.2.log",
    "fix_build.log",
    "env.txt",
    "fix.diff",
    "manifest.json",
    "verdict.json"
  ]
}