src/share/vm/prims/jniCheck.cpp

rev 1876 : 6539281 -Xcheck:jni should validate char* argument to ReleaseStringUTFChars

*** 1286,1321 ****
      jsize result = UNCHECKED()->GetStringLength(env,str);
      functionExit(env);
      return result;
  JNI_END
  
  JNI_ENTRY_CHECKED(const jchar *,
    checked_jni_GetStringChars(JNIEnv *env,
                               jstring str,
                               jboolean *isCopy))
      functionEnter(thr);
      IN_VM(
        checkString(thr, str);
      )
      const jchar *result = UNCHECKED()->GetStringChars(env,str,isCopy);
      functionExit(env);
!     return result;
  JNI_END
  
  JNI_ENTRY_CHECKED(void,
    checked_jni_ReleaseStringChars(JNIEnv *env,
                                   jstring str,
                                   const jchar *chars))
      functionEnterExceptionAllowed(thr);
      IN_VM(
        checkString(thr, str);
      )
!     /* cannot check validity of copy, unless every request is logged by
!      * checking code.  Implementation of this check is deferred until a
!      * subsequent release.
!      */
!     UNCHECKED()->ReleaseStringChars(env,str,chars);
      functionExit(env);
  JNI_END
  
  JNI_ENTRY_CHECKED(jstring,
    checked_jni_NewStringUTF(JNIEnv *env,
--- 1286,1333 ----
      jsize result = UNCHECKED()->GetStringLength(env,str);
      functionExit(env);
      return result;
  JNI_END
  
+ // Arbitrary (but well-known) tag
+ #define STRING_TAG 0x47114711
+ 
  JNI_ENTRY_CHECKED(const jchar *,
    checked_jni_GetStringChars(JNIEnv *env,
                               jstring str,
                               jboolean *isCopy))
      functionEnter(thr);
      IN_VM(
        checkString(thr, str);
      )
      const jchar *result = UNCHECKED()->GetStringChars(env,str,isCopy);
+ 
+     size_t len = UNCHECKED()->GetStringLength(env,str) + 1; // + 1 for NULL termination
+     jint* tagLocation = (jint*) AllocateHeap(len * sizeof(jchar) + sizeof(jint), "checked_jni_GetStringChars"); 
+     *tagLocation = STRING_TAG;
+     jchar* newResult = (jchar*) (tagLocation + 1);
+     memcpy(newResult, result, len * sizeof(jchar));
+     // Avoiding call to UNCHECKED()->ReleaseStringChars() since that will fire unexpected dtrace probes
+     FreeHeap((char*)result);
+ 
      functionExit(env);
!     return newResult;
  JNI_END
  
  JNI_ENTRY_CHECKED(void,
    checked_jni_ReleaseStringChars(JNIEnv *env,
                                   jstring str,
                                   const jchar *chars))
      functionEnterExceptionAllowed(thr);
      IN_VM(
        checkString(thr, str);
      )
!     jint *tagLocation = ((jint*) chars) - 1;
!     if (*tagLocation != STRING_TAG) {
!        NativeReportJNIFatalError(thr, "ReleaseStringChars called on something not allocated by GetStringChars");
!     }
!     UNCHECKED()->ReleaseStringChars(env,str,(const jchar*)tagLocation);
      functionExit(env);
  JNI_END
  
  JNI_ENTRY_CHECKED(jstring,
    checked_jni_NewStringUTF(JNIEnv *env,
*** 1336,1371 ****
      jsize result = UNCHECKED()->GetStringUTFLength(env,str);
      functionExit(env);
      return result;
  JNI_END
  
  JNI_ENTRY_CHECKED(const char *,
    checked_jni_GetStringUTFChars(JNIEnv *env,
                                  jstring str,
                                  jboolean *isCopy))
      functionEnter(thr);
      IN_VM(
        checkString(thr, str);
      )
      const char *result = UNCHECKED()->GetStringUTFChars(env,str,isCopy);
      functionExit(env);
!     return result;
  JNI_END
  
  JNI_ENTRY_CHECKED(void,
    checked_jni_ReleaseStringUTFChars(JNIEnv *env,
                                      jstring str,
                                      const char* chars))
      functionEnterExceptionAllowed(thr);
      IN_VM(
        checkString(thr, str);
      )
!     /* cannot check validity of copy, unless every request is logged by
!      * checking code.  Implementation of this check is deferred until a
!      * subsequent release.
!      */
!     UNCHECKED()->ReleaseStringUTFChars(env,str,chars);
      functionExit(env);
  JNI_END
  
  JNI_ENTRY_CHECKED(jsize,
    checked_jni_GetArrayLength(JNIEnv *env,
--- 1348,1395 ----
      jsize result = UNCHECKED()->GetStringUTFLength(env,str);
      functionExit(env);
      return result;
  JNI_END
  
+ // Arbitrary (but well-known) tag - different than GetStringChars
+ #define STRING_UTF_TAG 0x48124812
+ 
  JNI_ENTRY_CHECKED(const char *,
    checked_jni_GetStringUTFChars(JNIEnv *env,
                                  jstring str,
                                  jboolean *isCopy))
      functionEnter(thr);
      IN_VM(
        checkString(thr, str);
      )
      const char *result = UNCHECKED()->GetStringUTFChars(env,str,isCopy);
+ 
+     size_t len = strlen(result) + 1; // + 1 for NULL termination
+     jint* tagLocation = (jint*) AllocateHeap(len + sizeof(jint), "checked_jni_GetStringUTFChars");
+     *tagLocation = STRING_UTF_TAG;
+     char* newResult = (char*) (tagLocation + 1);
+     strcpy(newResult, result);
+     // Avoiding call to UNCHECKED()->ReleaseStringUTFChars() since that will fire unexpected dtrace probes
+     FreeHeap((char*)result);
+ 
      functionExit(env);
!     return newResult;
  JNI_END
  
  JNI_ENTRY_CHECKED(void,
    checked_jni_ReleaseStringUTFChars(JNIEnv *env,
                                      jstring str,
                                      const char* chars))
      functionEnterExceptionAllowed(thr);
      IN_VM(
        checkString(thr, str);
      )
!     jint* tagLocation = ((jint*) chars) - 1;
!     if (*tagLocation != STRING_UTF_TAG) {
!        NativeReportJNIFatalError(thr, "ReleaseStringUTFChars called on something not allocated by GetStringUTFChars");
!     }
!     UNCHECKED()->ReleaseStringUTFChars(env,str,(const char*)tagLocation);
      functionExit(env);
  JNI_END
  
  JNI_ENTRY_CHECKED(jsize,
    checked_jni_GetArrayLength(JNIEnv *env,