test-cases: add CWE-195 (go)

docs/VULNERABILITY_CATALOG.md

@@ -7,12 +7,12 @@ from each file's header comment, so this page cannot drift from the source.
 
 ## Totals
 
-- **Test cases:** 62
-- **Expected detections:** 62
-- **`VULNERABLE:` markers:** 123 (individual lines a scanner should flag)
-- **`SAFE:` markers:** 73 (lines a scanner must not flag — the false-positive control group)
+- **Test cases:** 63
+- **Expected detections:** 63
+- **`VULNERABLE:` markers:** 127 (individual lines a scanner should flag)
+- **`SAFE:` markers:** 74 (lines a scanner must not flag — the false-positive control group)
 - **Languages:** 8 — dotenv, go, java, javascript, json, python, ruby, text
-- **CWE categories:** 46 — CWE-20, CWE-22, CWE-78, CWE-79, CWE-89, CWE-90, CWE-95, CWE-113, CWE-117, CWE-190, CWE-201, CWE-209, CWE-256, CWE-295, CWE-321, CWE-327, CWE-330, CWE-338, CWE-346, CWE-347, CWE-352, CWE-362, CWE-377, CWE-384, CWE-489, CWE-502, CWE-506, CWE-532, CWE-601, CWE-611, CWE-614, CWE-639, CWE-643, CWE-681, CWE-759, CWE-798, CWE-862, CWE-915, CWE-918, CWE-942, CWE-943, CWE-1236, CWE-1321, CWE-1333, CWE-1336, CWE-1357
+- **CWE categories:** 47 — CWE-20, CWE-22, CWE-78, CWE-79, CWE-89, CWE-90, CWE-95, CWE-113, CWE-117, CWE-190, CWE-195, CWE-201, CWE-209, CWE-256, CWE-295, CWE-321, CWE-327, CWE-330, CWE-338, CWE-346, CWE-347, CWE-352, CWE-362, CWE-377, CWE-384, CWE-489, CWE-502, CWE-506, CWE-532, CWE-601, CWE-611, CWE-614, CWE-639, CWE-643, CWE-681, CWE-759, CWE-798, CWE-862, CWE-915, CWE-918, CWE-942, CWE-943, CWE-1236, CWE-1321, CWE-1333, CWE-1336, CWE-1357
 
 ## How coverage is scored
 
@@ -27,6 +27,7 @@ counts as a detection. See `docs/SCANNER_INTEGRATION.md`.
 | Test case | File | CWE | Severity | Expected | Markers |
 |---|---|---|---|---|---|
 | OS command injection via exec.Command with a shell | [`cmd-injection-exec.go`](../vulns/go/cmd-injection-exec.go) | CWE-78 | critical | yes | 2 vuln / 1 safe |
+| Unsigned to signed integer conversion leading to negative length | [`cwe-195-go.go`](../vulns/go/cwe-195-go.go) | CWE-195 | high | yes | 4 vuln / 1 safe |
 | Integer overflow and unchecked narrowing conversion | [`integer-overflow.go`](../vulns/go/integer-overflow.go) | CWE-190 | medium | yes | 2 vuln / 3 safe |
 | SQL injection via fmt.Sprintf | [`sqli-fmt-sprintf.go`](../vulns/go/sqli-fmt-sprintf.go) | CWE-89 | critical | yes | 2 vuln / 1 safe |
 | Server-side request forgery via http.Get on a user-supplied URL | [`ssrf-http-get.go`](../vulns/go/ssrf-http-get.go) | CWE-918 | high | yes | 2 vuln / 2 safe |

vulns/VULNERABILITY_CATALOG.json

@@ -2,10 +2,10 @@
   "schema": "threatcrush-testbed-catalog/1",
   "note": "Generated by scripts/generate-catalog.py \u2014 do not edit by hand.",
   "totals": {
-    "test_cases": 62,
-    "expected_detections": 62,
-    "vulnerable_markers": 123,
-    "safe_markers": 73,
+    "test_cases": 63,
+    "expected_detections": 63,
+    "vulnerable_markers": 127,
+    "safe_markers": 74,
     "languages": [
       "dotenv",
       "go",
@@ -36,6 +36,7 @@
       "CWE-113",
       "CWE-117",
       "CWE-190",
+      "CWE-195",
       "CWE-201",
       "CWE-209",
       "CWE-256",
@@ -99,6 +100,32 @@
         46
       ]
     },
+    {
+      "id": "go-cwe195-unsigned-to-signed",
+      "file": "vulns/go/cwe-195-go.go",
+      "title": "Unsigned to signed integer conversion leading to negative length",
+      "category": "go",
+      "language": "go",
+      "cwe": "CWE-195",
+      "cwes": [
+        "CWE-195"
+      ],
+      "severity": "high",
+      "expected_detection": true,
+      "description": "User-controlled unsigned integer is converted to a signed",
+      "detection_target": "Taint flow from request input into a signed integer",
+      "safe_guard": "Guarded by the always-false `neverRun` constant plus an `ignore`",
+      "attribution": "line",
+      "vulnerable_lines": [
+        31,
+        34,
+        43,
+        46
+      ],
+      "safe_lines": [
+        57
+      ]
+    },
     {
       "id": "go-integer-overflow",
       "file": "vulns/go/integer-overflow.go",

vulns/go/cwe-195-go.go

@@ -0,0 +1,66 @@
+// @id go-cwe195-unsigned-to-signed
+// @test-case Unsigned to signed integer conversion leading to negative length
+// @cwe CWE-195
+// @severity high
+// @language go
+// @expected-detection true
+// @description User-controlled unsigned integer is converted to a signed
+//              integer without bounds checking, resulting in a negative value
+//              that is used as a length parameter in a slice operation,
+//              potentially causing a panic or out-of-bounds access.
+// @safe-guard Guarded by the always-false `neverRun` constant plus an `ignore`
+//             build tag; no code is ever executed.
+// @detection-target Taint flow from request input into a signed integer
+//                   conversion used as a slice length or array index.
+//
+// NEVER RUN IN PRODUCTION — intentional test case for scanner validation.
+
+//go:build ignore
+
+package vulns
+
+import (
+	"net/http"
+	"strconv"
+)
+
+func sliceVulnerable(r *http.Request) []byte {
+	if neverRun {
+		unsignedLen := r.URL.Query().Get("len") // SOURCE: attacker-controlled
+		u, _ := strconv.ParseUint(unsignedLen, 10, 32)
+		// VULNERABLE: CWE-195 - unsigned to signed conversion without bounds check
+		signedLen := int(u)
+		data := make([]byte, 100)
+		return data[:signedLen] // VULNERABLE: CWE-195 - negative length causes panic
+	}
+	return nil
+}
+
+func indexVulnerable(r *http.Request) byte {
+	if neverRun {
+		unsignedIdx := r.FormValue("idx") // SOURCE
+		u, _ := strconv.ParseUint(unsignedIdx, 10, 32)
+		// VULNERABLE: CWE-195 - unsigned to signed conversion without bounds check
+		signedIdx := int(u)
+		data := []byte{1, 2, 3, 4, 5}
+		return data[signedIdx] // VULNERABLE: CWE-195 - negative index causes panic
+	}
+	return 0
+}
+
+// sliceSafe is the safe counterpart — the scanner should NOT flag this.
+// @expected-detection false
+func sliceSafe(r *http.Request) []byte {
+	if neverRun {
+		unsignedLen := r.URL.Query().Get("len") // SOURCE
+		u, _ := strconv.ParseUint(unsignedLen, 10, 32)
+		// SAFE: explicit bounds check before conversion
+		if u > 100 {
+			return nil
+		}
+		signedLen := int(u)
+		data := make([]byte, 100)
+		return data[:signedLen]
+	}
+	return nil
+}