tor-browser

commit 975867c77a43530175e82133cfbe13df7c8ab600
parent c35192456a26bb94d66cd75be9f3c32d5db4ddf0
Author: Ted Campbell <tcampbell@mozilla.com>
Date:   Thu, 27 Nov 2025 20:08:02 +0000

Bug 2002706 - Don't crash Fenix crashreporter on unserializable exceptions r=android-reviewers,Roger

Not all Throwable are Serializable which was causing the A-C CrashReporter to
itself crash when stashing a crash report in local Room storage. Instead, create
a placeholder Throwable with same stack but encode type as string.

simpler crash recovery

Differential Revision: https://phabricator.services.mozilla.com/D274249

Diffstat:
M
mobile/android/android-components/components/lib/crash/src/main/java/mozilla/components/lib/crash/db/CrashEntity.kt
 | 
19
+++++++++++++++----
M
mobile/android/android-components/components/lib/crash/src/test/java/mozilla/components/lib/crash/CrashReporterTest.kt
 | 
43
+++++++++++++++++++++++++++++++++++++++++++

2 files changed, 58 insertions(+), 4 deletions(-)
diff --git a/mobile/android/android-components/components/lib/crash/src/main/java/mozilla/components/lib/crash/db/CrashEntity.kt b/mobile/android/android-components/components/lib/crash/src/main/java/mozilla/components/lib/crash/db/CrashEntity.kt
@@ -12,6 +12,7 @@ import mozilla.components.lib.crash.Crash
 import mozilla.components.support.base.ext.getStacktraceAsString
 import java.io.ByteArrayInputStream
 import java.io.ByteArrayOutputStream
+import java.io.NotSerializableException
 import java.io.ObjectInputStream
 import java.io.ObjectOutputStream
 import mozilla.components.concept.base.crash.Breadcrumb as CrashBreadcrumb
@@ -176,11 +177,21 @@ internal fun Crash.toEntity(): CrashEntity {
 }
 
 private fun Throwable.serialize(): ByteArray {
-    val byteArrayOutputStream = ByteArrayOutputStream()
-    ObjectOutputStream(byteArrayOutputStream).use { oos ->
-        oos.writeObject(this)
+    return try {
+        val byteArrayOutputStream = ByteArrayOutputStream()
+        ObjectOutputStream(byteArrayOutputStream).use { oos ->
+            oos.writeObject(this)
+        }
+        byteArrayOutputStream.toByteArray()
+    } catch (e: NotSerializableException) {
+        // If throwable isn't serializable, then use a placeholder Throwable with
+        // the same stack and include basic name / message data. This gives us
+        // at least some data to understand these crashes in the wild.
+        val innerMessage = "${javaClass.name}: $message"
+        val altThrowable = CrashReporterUnableToRestoreException(innerMessage)
+        altThrowable.stackTrace = stackTrace.clone()
+        altThrowable.serialize()
     }
-    return byteArrayOutputStream.toByteArray()
 }
 
 private fun ByteArray.deserializeThrowable(): Throwable {
diff --git a/mobile/android/android-components/components/lib/crash/src/test/java/mozilla/components/lib/crash/CrashReporterTest.kt b/mobile/android/android-components/components/lib/crash/src/test/java/mozilla/components/lib/crash/CrashReporterTest.kt
@@ -15,7 +15,10 @@ import mozilla.components.concept.base.crash.Breadcrumb
 import mozilla.components.lib.crash.db.CrashDao
 import mozilla.components.lib.crash.db.CrashDatabase
 import mozilla.components.lib.crash.db.CrashEntity
+import mozilla.components.lib.crash.db.CrashReporterUnableToRestoreException
 import mozilla.components.lib.crash.db.CrashType
+import mozilla.components.lib.crash.db.toCrash
+import mozilla.components.lib.crash.db.toEntity
 import mozilla.components.lib.crash.service.CrashReporterService
 import mozilla.components.lib.crash.service.CrashTelemetryService
 import mozilla.components.support.test.any
@@ -27,6 +30,7 @@ import mozilla.components.support.test.robolectric.testContext
 import mozilla.components.support.test.rule.MainCoroutineRule
 import mozilla.components.support.test.rule.runTestOnMain
 import org.junit.After
+import org.junit.Assert.assertArrayEquals
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertNotEquals
@@ -1433,6 +1437,31 @@ class CrashReporterTest {
         assertEquals(crashReporter.findCrashReports(crashIDs).get(0).uuid, crashEntity1.uuid)
         assertEquals(crashReporter.findCrashReports(crashIDs).get(1).uuid, crashEntity3.uuid)
     }
+
+    @Test
+    fun `Round-trip through CrashEntity preserves (serializable) Throwable info`() {
+        val crash = createUncaughtExceptionCrash()
+
+        val entity = crash.toEntity()
+        val otherCrash = entity.toCrash() as Crash.UncaughtExceptionCrash
+
+        assertEquals(crash.throwable.javaClass, otherCrash.throwable.javaClass)
+        assertEquals(crash.throwable.message, otherCrash.throwable.message)
+        assertArrayEquals(crash.throwable.stackTrace, otherCrash.throwable.stackTrace)
+    }
+
+    @Test
+    fun `Round-trip through CrashEntity for unserializable Throwable preserves stack`() {
+        val crash = createUnserializableUncaughtExceptionCrash()
+        val expectedMessage = "${crash.throwable.javaClass.name}: This exception has a bad field!"
+
+        val entity = crash.toEntity()
+        val otherCrash = entity.toCrash() as Crash.UncaughtExceptionCrash
+
+        assertTrue(otherCrash.throwable is CrashReporterUnableToRestoreException)
+        assertEquals(expectedMessage, otherCrash.throwable.message)
+        assertArrayEquals(crash.throwable.stackTrace, otherCrash.throwable.stackTrace)
+    }
 }
 
 private fun createUncaughtExceptionCrash(): Crash.UncaughtExceptionCrash {
@@ -1442,3 +1471,17 @@ private fun createUncaughtExceptionCrash(): Crash.UncaughtExceptionCrash {
         ArrayList(),
     )
 }
+
+private class UnserializableException(
+    @Suppress("unused")
+    val badField: Thread = Thread.currentThread(),
+) : Exception("This exception has a bad field!")
+
+private fun createUnserializableUncaughtExceptionCrash(): Crash.UncaughtExceptionCrash {
+    val throwable = UnserializableException()
+    return Crash.UncaughtExceptionCrash(
+        0,
+        throwable,
+        ArrayList(),
+    )
+}