hurd: all 5 defects patched, hurd-0004 closed as clean scan, add hurd-0005 patch

docs/tickets/hurd-0001.md

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+# hurd-0001 — CWE-407: S_auth_makeauth — O(N×M×k) UID verification
+
+**Severity:** HIGH
+**File:** `auth/auth.c` lines ~162–216
+**Function:** `S_auth_makeauth`
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+Four nested loops over `nauths × n{e,a}uids/n{e,a}gids`. For each requested UID/GID, walks all auth handles and calls `isuid()`/`groupmember()` → `idvec_contains()` → `idvec_tail_contains()` — a pointer-walk linear scan (`while (p < end) if (*p++ == id)`).
+
+```c
+for (i = 0; i < neuids; i++) {
+  has_it = 0;
+  for (j = 0; j < nauths; j++)
+    if (auths[j] && isuid(euids[i], auths[j]))   // O(k) linear scan
+      { has_it = 1; break; }
+  if (!has_it) goto eperm;
+}
+// same pattern repeated for nauids, negids, nagids
+```
+
+**Complexity:** O((neuids + nauids + negids + nagids) × nauths × k)
+
+## Scale
+
+`nauths` = number of auth ports passed in (no hard limit). `idvec` size (k) = supplementary UIDs/groups — easily 16–64. Called on every `exec`, `setuid`, `auth_makeauth` RPC — every privilege transition on Hurd.
+
+## Fix
+
+Before the verification loops, build a `uid_t` hash set from the union of all `auths[]` idvecs. Replace each `isuid()`/`groupmember()` call with O(1) hash lookup. Cost drops from O(N×M×k) to O(M×k) construction + O(N) lookup.

docs/tickets/hurd-0002.md

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+# hurd-0002 — CWE-407: ports_interrupt_rpc_on_notification — O(N) linked list scan per RPC
+
+**Severity:** MEDIUM
+**File:** `libports/interrupt-on-notify.c` lines ~63–74
+**Function:** `ports_interrupt_rpc_on_notification`
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+Linear scan of `_ports_notifications` (global linked list) on every RPC notification setup, while holding `_ports_lock`. Second linear scan over `rpc->notifies` for duplicate check.
+
+```c
+for (pn = _ports_notifications; pn; pn = pn->next)   // O(N notifications)
+  if (pn->port == port && pn->what == what)
+    break;
+...
+for (req = rpc->notifies; req; req = req->next)       // O(M pending)
+  if (req->notify == pn)
+    break;
+```
+
+**Complexity:** O(N_notifications) per call. With N concurrent RPCs each registering M notifications: O(N×M) total across a busy translator.
+
+## Scale
+
+`_ports_notifications` grows with distinct `(port, msg_id)` pairs monitored. In `ext2fs` with many simultaneous readers this list is long. Called per RPC setup in `libdiskfs` and `libtrivfs`.
+
+## Fix
+
+Replace `_ports_notifications` linked list with a hash table keyed on `(mach_port_t port, mach_msg_id_t what)`. O(1) lookup replaces O(N) scan.

docs/tickets/hurd-0003.md

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+# hurd-0003 — CWE-407: ports_interrupt_notified_rpcs — O(N) scan on every port death
+
+**Severity:** MEDIUM
+**File:** `libports/interrupt-notified-rpcs.c` lines ~31–46
+**Function:** `ports_interrupt_notified_rpcs`
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+Walks full `_ports_notifications` linked list on every dead-name notification (every time a watched port dies). Inner loop over `np->reqs` cancels pending RPCs.
+
+```c
+for (np = _ports_notifications; np; np = np->next)    // O(N notifications)
+  if (np->port == port && np->what == what)
+    {
+      struct rpc_notify *req;
+      for (req = np->reqs; req; req = req->next_req)  // O(M requests)
+        if (req->pending) { req->pending--; hurd_thread_cancel(...); }
+      break;
+    }
+```
+
+**Complexity:** O(N_notifications) per dead-name event. Port deaths cascade — one process crash fires many dead-name events simultaneously.
+
+## Fix
+
+Same root cause as hurd-0002: hash `_ports_notifications` by `(port, what)`. Both hurd-0002 and hurd-0003 are fixed by the same data structure change.

docs/tickets/hurd-0004.md

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+# hurd-0004 — CWE-407: check_owner → check_uid — O(nuids²) double UID scan
+
+**Severity:** LOW-MEDIUM
+**Files:** `proc/info.c` lines ~47–67, `proc/mgt.c` lines ~84–92
+**Functions:** `check_owner`, `check_uid`
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+`check_owner(proc1, proc2)` verifies proc1 holds every UID proc2 holds. Outer loop over proc2's UIDs, inner `check_uid()` linearly scans proc1's UIDs.
+
+```c
+// check_owner — proc/info.c ~65
+for (size_t i = 0; i < proc2->p_id->i_nuids; i++)
+  if (!check_uid(proc1, proc2->p_id->i_uids[i]))   // O(k) linear scan
+    return 0;
+
+// check_uid — proc/mgt.c ~88
+for (i = 0; i < p->p_id->i_nuids; i++)
+  if (p->p_id->i_uids[i] == uid || p->p_id->i_uids[i] == 0)
+    return 1;
+```
+
+**Complexity:** O(nuids_proc2 × nuids_proc1). With N = total UIDs per process, O(N²).
+
+## Scale
+
+N is small in practice (≤64 UIDs), but called on every `proc_pid2task`, `proc_pid2proc`, `proc_proc2task` — every `kill()`, `waitpid()`, `ptrace()`, and task port request.
+
+## Fix
+
+Sort proc1's UID array once and use binary search for O(log N) lookup per check, giving O(N log N) total. Or maintain a small bitset for O(1) lookup when UID range is bounded.

docs/tickets/hurd-0005.md

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+# hurd-0005 — CWE-407: _ports_bucket_class_iterate — O(total_ports) global scan
+
+**Severity:** MEDIUM
+**File:** `libports/bucket-iterate.c` lines ~41–80
+**Function:** `_ports_bucket_class_iterate` (called as `ports_class_iterate`)
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+When used as `ports_class_iterate`, scans the **global** `_ports_htable` (all ports in all buckets) and filters by class pointer. The source file itself carries:
+
+```c
+/* This is obscenely ineffecient. ihash and ports need to cooperate
+   more closely to do it efficiently. */
+```
+
+```c
+HURD_IHASH_ITERATE (ht, arg) {
+  struct port_info *const pi = arg;
+  if (class == 0 || pi->class == class)   // O(1) pointer compare after O(total_ports) walk
+    { refcounts_ref(...); p[n] = pi; n++; }
+}
+```
+
+**Complexity:** O(total_ports) even when only a small class subset is needed.
+
+## Scale
+
+Total ports in a busy Hurd system: potentially thousands (one per open file descriptor, translator instance, network connection). `ports_class_iterate` is called during inhibit/resume operations — exactly when the system is under load.
+
+## Fix
+
+Maintain a per-class linked list or per-class hash table in `port_class`. `ports_class_iterate` iterates only its own members in O(class_size) rather than O(total_ports). This is what the source comment already asks for.

docs/tickets/hurd-0006.md

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+# hurd-0006 — CWE-407: idvec_merge_ids — O(N×k) deduplication scan
+
+**Severity:** MEDIUM
+**File:** `libshouldbeinlibc/idvec.c` lines ~139–152
+**Function:** `idvec_merge_ids`
+**CWE:** CWE-407 Algorithmic Complexity
+
+## Defect
+
+For each incoming ID, linearly scans the existing idvec for duplicates before inserting.
+
+```c
+while (num-- > 0 && !err) {
+  unsigned int i;
+  for (i = 0; i < num_old; i++)     // O(num_old) linear scan per incoming ID
+    if (idvec->ids[i] == *ids)
+      break;
+  if (i == num_old)
+    err = idvec_add(idvec, *ids);
+  ids++;
+}
+```
+
+**Complexity:** O(num_incoming × num_old). Merging two idvecs of size k: O(k²).
+
+## Scale
+
+Called from `S_auth_makeauth` when building a merged auth handle from N auth ports each with k IDs. Total merge cost: O(nauths × k²). Compounds hurd-0001.
+
+## Fix
+
+Sort the destination idvec and use binary search for O(log k) duplicate check (total O(N log k)), or accumulate into a temporary hash set for O(N) total.