[Android] Handle X509ChainContext creation failures (dotnet#128651)

An Android production app reported a native abort while building an
X.509 chain on arm64. The available tombstone snippet showed the process
aborting in `AndroidCryptoNative_X509ChainBuild` from `pal_x509chain.c`,
with the native guard reporting that parameter `ctx` was not a valid
pointer. The report did not include a repro or full tombstone, but the
observed failure mode means managed code reached the native build entry
point with a null `X509ChainContext*`.

```
Thread
/__w/1/s/src/native/libs/System.Security.Cryptography.Native.Android/pal_x509chain.c:113 (AndroidCryptoNative_X509ChainBuild): Parameter 'ctx' must be a valid pointer
 
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
pid: 0, tid: 31609 >>> com.app.name <<<
 
backtrace:
  #00  pc 0x000000000002232c  /system/lib64/libc.so (abort+116)
  #1  pc 0x0000000000021fe8  [removed]-KwPZdoEumri00C7kBm3pQw==/lib/arm64/libSystem.Security.Cryptography.Native.Android.so
  #2  pc 0x00000000000220b0  [removed]-KwPZdoEumri00C7kBm3pQw==/lib/arm64/libSystem.Security.Cryptography.Native.Android.so (AndroidCryptoNative_X509ChainBuild+88)
  #3  pc 0x000000000000cfcc
```

`X509ChainContext` is created by
`AndroidCryptoNative_X509ChainCreateContext`. That initialization can
fail if Android certificate store setup or PKIX parameter construction
throws, or if required JNI global references cannot be created.
Previously, the managed Android chain path stored the returned
`SafeHandle` without checking whether context creation failed, so a
later build could pass a null native context to
`AndroidCryptoNative_X509ChainBuild` and terminate the app process.

This change makes context creation fail gracefully:

- The native create path checks Java exceptions around object creation
and method calls more consistently.
- Partial native contexts are destroyed if global-reference creation
fails.
- The Android interop wrapper checks the returned chain context
immediately, including a null safe-handle return, and throws
`CryptographicException` if initialization failed.

No regression test is included because the reliable failure modes depend
on Android platform/provider state or artificial fault injection, and a
test hook would be fragile and not representative.

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Kevin Jones <kevin@vcsjones.com>

Author: 3 people

src/libraries/Common/src/Interop/Android/System.Security.Cryptography.Native.Android/Interop.X509Chain.cs

@@ -13,11 +13,24 @@ internal static partial class Interop
     internal static partial class AndroidCrypto
     {
         [LibraryImport(Libraries.AndroidCryptoNative, EntryPoint = "AndroidCryptoNative_X509ChainCreateContext")]
-        internal static partial SafeX509ChainContextHandle X509ChainCreateContext(
+        private static partial SafeX509ChainContextHandle X509ChainCreateContext(
             SafeX509Handle cert,
             IntPtr[] extraStore,
             int extraStoreLen);
 
+        internal static SafeX509ChainContextHandle X509ChainCreateContext(SafeX509Handle cert, IntPtr[] extraStore)
+        {
+            SafeX509ChainContextHandle chainContext = X509ChainCreateContext(cert, extraStore, extraStore.Length);
+
+            if (chainContext.IsInvalid)
+            {
+                chainContext.Dispose();
+                throw new CryptographicException(SR.Cryptography_AndroidX509ChainContextInitializationFailed);
+            }
+
+            return chainContext;
+        }
+
         [LibraryImport(Libraries.AndroidCryptoNative, EntryPoint = "AndroidCryptoNative_X509ChainDestroyContext")]
         internal static partial void X509ChainDestroyContext(IntPtr ctx);
 

src/libraries/System.Security.Cryptography/src/Resources/Strings.resx

@@ -237,6 +237,9 @@
   <data name="Cryptography_AlgorithmTypesMustBeVisible" xml:space="preserve">
     <value>Algorithms added to CryptoConfig must be accessible from outside their assembly.</value>
   </data>
+  <data name="Cryptography_AndroidX509ChainContextInitializationFailed" xml:space="preserve">
+    <value>The Android X.509 certificate chain could not be initialized.</value>
+  </data>
   <data name="Cryptography_ArgDSARequiresDSAKey" xml:space="preserve">
     <value>Keys used with the DSACng algorithm must have an algorithm group of DSA.</value>
   </data>

src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/X509Certificates/ChainPal.Android.cs

@@ -141,8 +141,7 @@ internal void Initialize(
 
                     _chainContext = Interop.AndroidCrypto.X509ChainCreateContext(
                         ((AndroidCertificatePal)cert).SafeHandle,
-                        extraCerts,
-                        extraCerts.Length);
+                        extraCerts);
 
                     if (useCustomRootTrust)
                     {

src/native/libs/System.Security.Cryptography.Native.Android/pal_x509chain.c

@@ -39,7 +39,7 @@ X509ChainContext* AndroidCryptoNative_X509ChainCreateContext(jobject /*X509Certi
     JNIEnv* env = GetJNIEnv();
 
     X509ChainContext* ret = NULL;
-    INIT_LOCALS(loc, keyStoreType, keyStore, targetSel, params, certList, certStoreType, certStoreParams, certStore);
+    INIT_LOCALS(loc, keyStoreType, keyStore, targetSel, params, certList, certStoreType, certStoreParams, certStore, errorList);
 
     // String keyStoreType = "AndroidCAStore";
     // KeyStore keyStore = KeyStore.getInstance(keyStoreType);
@@ -53,7 +53,9 @@ X509ChainContext* AndroidCryptoNative_X509ChainCreateContext(jobject /*X509Certi
     // X509CertSelector targetSel = new X509CertSelector();
     // targetSel.setCertificate(cert);
     loc[targetSel] = (*env)->NewObject(env, g_X509CertSelectorClass, g_X509CertSelectorCtor);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
     (*env)->CallVoidMethod(env, loc[targetSel], g_X509CertSelectorSetCertificate, cert);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
 
     // PKIXBuilderParameters params = new PKIXBuilderParameters(keyStore, targetSelector);
     loc[params] = (*env)->NewObject(
@@ -66,10 +68,13 @@ X509ChainContext* AndroidCryptoNative_X509ChainCreateContext(jobject /*X509Certi
     //     certList.add(extraStore[i]);
     // }
     loc[certList] = (*env)->NewObject(env, g_ArrayListClass, g_ArrayListCtorWithCapacity, extraStoreLen);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
     (*env)->CallBooleanMethod(env, loc[certList], g_ArrayListAdd, cert);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
     for (int i = 0; i < extraStoreLen; ++i)
     {
         (*env)->CallBooleanMethod(env, loc[certList], g_ArrayListAdd, extraStore[i]);
+        ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
     }
 
     // String certStoreType = "Collection";
@@ -78,16 +83,21 @@ X509ChainContext* AndroidCryptoNative_X509ChainCreateContext(jobject /*X509Certi
     loc[certStoreType] = make_java_string(env, "Collection");
     loc[certStoreParams] = (*env)->NewObject(
         env, g_CollectionCertStoreParametersClass, g_CollectionCertStoreParametersCtor, loc[certList]);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
     loc[certStore] = (*env)->CallStaticObjectMethod(
         env, g_CertStoreClass, g_CertStoreGetInstance, loc[certStoreType], loc[certStoreParams]);
     ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
 
     // params.addCertStore(certStore);
     (*env)->CallVoidMethod(env, loc[params], g_PKIXBuilderParametersAddCertStore, loc[certStore]);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
+
+    loc[errorList] = (*env)->NewObject(env, g_ArrayListClass, g_ArrayListCtor);
+    ON_EXCEPTION_PRINT_AND_GOTO(cleanup);
 
     ret = xcalloc(1, sizeof(X509ChainContext));
     ret->params = AddGRef(env, loc[params]);
-    ret->errorList = ToGRef(env, (*env)->NewObject(env, g_ArrayListClass, g_ArrayListCtor));
+    ret->errorList = AddGRef(env, loc[errorList]);
 
 cleanup:
     RELEASE_LOCALS(loc, env);