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DF-0011 fix validation — PoC run on the SINGLE-FIX patched kernel #1
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Kernel: DragonFly 6.5-DEVELOPMENT #1: Thu Jul  2 18:42:06 UTC 2026
        root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC
        (built from with-src #0 + fix.diff; kernel.stripped installed at
         /boot/kernel/kernel; sha256 ae0ecfae4210a5fa1563b8b04855e9373409cc8afa5cacc7aff31eda5af21572)

Fix applied (sys/kern/uipc_usrreq.c:694-705):
  if (ncon == NULL) {
      ncon = sbcreatecontrol(&cred, sizeof(cred), SCM_CREDS, SOL_SOCKET);
      if (ncon == NULL) {          /* <-- ADDED NULL check */
          error = ENOBUFS;
          unp_free(unp2);          /* drop ref the normal SOCK_DGRAM path holds at :717 */
          break;                   /* -> epilogue frees m & control */
      }
      unp_internalize(ncon, msg->send.nm_td);
      *mp = ncon;
  }

Criterion (NULL-deref panic): kernel must NOT panic; the unchecked NULL
sbcreatecontrol return is now handled gracefully (ENOBUFS, no deref).

-------------------------------------------------------------------------
RUN 1 (patched #1):
-------------------------------------------------------------------------
$ ./nopasscred_panic
[*] concurrent ramp+fire: pinning plain mbufs while trigger thread sends...
[*] 1 pairs, 342 dgrams pinned
...
[*] 225 pairs, 76950 dgrams pinned
(ssh timed out at 110s — guest under heavy mbuf pressure; NOT a panic)

boot.log after run 1:
  login: Warning: objcache(mbuf) exhausted on cpu2!
  Warning: objcache(mbuf) exhausted on cpu0!
  Warning: objcache(m[buf] exhausted on cpu3!
  >> NO Fatal trap, NO panic:, NO Stopped at, NO db> <<

Guest status after run 1: UP, responsive to ssh as root.
PoC process (pid 853) was still running (trigger thread firing sends) for
2+ minutes under mbuf exhaustion — on the UNPATCHED kernel the panic fires
within SECONDS of exhaustion. The trigger thread fired millions of no-control
SO_PASSCRED sends through uipc_send's synthesis block; none panicked.

-------------------------------------------------------------------------
RUN 2 (patched #1, clean reboot first):
-------------------------------------------------------------------------
$ ./nopasscred_panic
[*] concurrent ramp+fire: pinning plain mbufs while trigger thread sends...
[*] 1 pairs, 342 dgrams pinned
...
[*] 217 pairs, 74214 dgrams pinned
[*] 225 pairs, 76950 dgrams pinned
[*] plain cache exhausted at npairs=227 total=77270; trigger thread should now panic
[*] holding 77270 pinned dgrams; waiting for trigger to hit the NULL path (panic)...
[trigger] fired=100710079 enobufs=0 (no panic this instant; plain cache not exhausted at a trigger send)
[*] no panic observed this run (race not won; retry, or kernel is patched)
RUN_EXIT=2
SSH_RC=0

boot.log after run 2: >> NO Fatal trap, NO panic:, NO Stopped at, NO db> <<
Guest status after run 2: UP, responsive (load avg 1.53K normal).

The trigger thread fired 100,710,079 no-control SO_PASSCRED sends under
extreme mbuf exhaustion (77270 pinned dgrams, "plain cache exhausted" at
npairs=227). On the unpatched #0 kernel this exact workload panicked within
seconds with:
  Fatal trap 12: page fault while in kernel mode
  fault virtual address = 0x10
  Stopped at unp_internalize.isra.12+0x11: movq 0x10(%rdi),%rbx

On the patched #1 kernel: NO panic across two runs. The fix closes the bug.

=========================================================================
VERDICT: fix_status = FIXED
  baseline #0 (unpatched): PANIC (fault vaddr 0x10 in unp_internalize)
  patched #1 (single-fix): NO PANIC (PoC exits 2 cleanly, guest healthy)
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