[Android] Add missing JNI exception checks across crypto PAL

[simonrozsival]

Note

This PR description was drafted by an AI assistant (GitHub Copilot CLI) based on the actual code changes in this branch. All code was authored interactively with Simon driving the design decisions.

Follow-up to #128777, which added the initial batch of JNI exception checks to the Android crypto PAL. This PR covers the remaining functions.

Summary

Adds missing JNI exception checks across the remaining functions in the Android cryptography PAL (src/native/libs/System.Security.Cryptography.Native.Android/). The work is based on a static audit of Call*Method / NewObject / Get*ArrayRegion-style JNI calls where a pending Java exception could otherwise leak back into managed code (undefined behavior for the next managed→native transition) or produce partial output.

Beyond adding the checks, the touched functions are tightened to follow three patterns already established elsewhere in the PAL:

1. ON_EXCEPTION_PRINT_AND_GOTO(label) immediately after each fallible JNI call. The macro both prints and clears the exception, so subsequent JNI calls on the cleanup path are safe.
2. INIT_LOCALS(loc, …) + a single cleanup:/RELEASE_LOCALS(loc, env) tail for local-ref hygiene, replacing ad-hoc jobject foo = NULL; declarations and scattered DeleteLocalRef calls.
3. No partial output state on failure — results are computed into locals and only promoted to caller-visible out-parameters / global refs on the success path.

Native changes

All under src/native/libs/System.Security.Cryptography.Native.Android/:

File	Functions
pal_x509chain.c	X509ChainBuild, X509ChainGetCertificateCount, X509ChainGetCertificates, X509ChainGetErrorCount, PopulateValidationError, X509ChainGetErrors, X509ChainSetCustomTrustStore, CreateCertPathFromAnchor, ValidateWithRevocation, and the error-capture branches
pal_bignum.c	BigNumToBinary, GetBigNumBytesIncludingPaddingByteForSign
pal_cipher.c	CipherSetKeyAndIV, CipherUpdateAAD, CipherUpdate (also releases the update output array on all paths)
pal_ecdsa.c	EcDsaSign (clear exception on the getPrivate() failure path)
pal_eckey.c	NewEcKeyFromKeys, EcKeyCreateByOid (converted to INIT_LOCALS + per-call checks), EcKeyGetCurveName
pal_hmac.c	DoFinal
pal_misc.c	GetRandomBytes
pal_pbkdf2.c	Pbkdf2 (clear the pending exception when NewDirectByteBuffer fails)
pal_sslstream.c	SSLStreamSetTargetHost, SSLStreamRead, SSLStreamRequestClientAuthentication, SSLStreamSetApplicationProtocols
pal_x509.c	X509Decode, X509DecodeCollection, X509GetContentType (check SetByteArrayRegion)

Managed changes

• Interop.X509Chain.cs — X509ChainGetErrorCount now returns a negative value when a JNI exception occurs (distinct from a legitimate count of 0); the wrapper throws CryptographicException in that case instead of silently reporting "no errors" (which would leave ChainStatus empty for a failed validation).
• Interop.Bignum.cs — AndroidCryptoNative_BigNumToBinary now returns -1 when a JNI exception occurs (the output must be treated as invalid — it may be zero-filled or only partially written); ExtractBignum throws CryptographicException rather than returning a corrupt buffer.

Testing

• Native build: android-arm64 Release — 0 warnings / 0 errors.
• Managed build: libs -os android -a arm64 -rf CoreCLR (includes System.Security.Cryptography) — 0 warnings / 0 errors.

CI will provide cross-architecture validation and device/emulator test runs.

[Copilot]

Pull request overview

This PR hardens the Android cryptography native PAL by adding missing JNI exception checks and tightening failure-path behavior so pending Java exceptions don’t leak into subsequent JNI transitions; it also updates managed interop to surface certain JNI failures as CryptographicException.

Changes:

• Added ON_EXCEPTION_PRINT_AND_GOTO(...) / CheckJNIExceptions(...) checks after additional fallible JNI calls across the Android crypto PAL.
• Adjusted native return conventions for some functions to better distinguish JNI-exception failures from legitimate “0 results”.
• Updated managed Android interop wrappers to throw when native indicates a JNI exception occurred (e.g., negative error counts / negative bignum conversions).

Show a summary per file

File	Description
src/native/libs/System.Security.Cryptography.Native.Android/pal_x509chain.c	Adds JNI exception checks and tightens error materialization/cleanup when building/validating chains and collecting errors.
src/native/libs/System.Security.Cryptography.Native.Android/pal_x509.c	Adds missing exception checks after byte-array population JNI calls.
src/native/libs/System.Security.Cryptography.Native.Android/pal_sslstream.c	Adds exception checks around additional SSLEngine/ByteBuffer JNI operations to avoid leaking pending exceptions.
src/native/libs/System.Security.Cryptography.Native.Android/pal_pbkdf2.c	Adds exception check after NewDirectByteBuffer and other JNI byte-buffer operations.
src/native/libs/System.Security.Cryptography.Native.Android/pal_misc.c	Converts to a ret/cleanup pattern and adds some exception checks in GetRandomBytes.
src/native/libs/System.Security.Cryptography.Native.Android/pal_hmac.c	Adds exception checks in the HMAC finalization path to prevent pending exceptions from escaping.
src/native/libs/System.Security.Cryptography.Native.Android/pal_eckey.c	Improves JNI exception handling for EC key creation and curve name extraction.
src/native/libs/System.Security.Cryptography.Native.Android/pal_ecdsa.c	Ensures exception state is cleared/observed on getPrivate() failure path.
src/native/libs/System.Security.Cryptography.Native.Android/pal_cipher.c	Adds exception checks in cipher update/AAD paths and ensures local refs are released on all paths.
src/native/libs/System.Security.Cryptography.Native.Android/pal_bignum.c	Adds exception checks and returns a negative result on JNI failure for bignum-to-binary conversion.
src/libraries/Common/src/Interop/Android/System.Security.Cryptography.Native.Android/Interop.X509Chain.cs	Throws when native indicates a JNI exception during chain error-count retrieval.
src/libraries/Common/src/Interop/Android/System.Security.Cryptography.Native.Android/Interop.Bignum.cs	Propagates native “JNI exception occurred” via CryptographicException instead of returning corrupt/zero-filled data.

Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 4

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Tagging subscribers to 'arch-android': @vitek-karas, @simonrozsival, @steveisok, @akoeplinger
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Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 2

[Copilot]

Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 1

[simonrozsival]

/azp run runtime-android

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Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 2