Fix read after free bug

[denisenkom]

Problem

JNA reads structure content for structures passed by reference. In this particular case since g_error_free function releases memory used by structure passed to it, this results in "read after free" bug. This leads to segmentation fault.

Here is example stack trace:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007ff81b607f12, pid=70813, tid=38659
...
C  [libsystem_platform.dylib+0xf12]  _platform_strlen+0x12
C  [jna8103589467894918189.tmp+0x5183]  Java_com_sun_jna_Native_getStringBytes+0x23
j  com.sun.jna.Native.getStringBytes(Lcom/sun/jna/Pointer;JJ)[B+0
j  com.sun.jna.Native.getString(Lcom/sun/jna/Pointer;JLjava/lang/String;)Ljava/lang/String;+6
j  com.sun.jna.Pointer.getString(JLjava/lang/String;)Ljava/lang/String;+3
j  com.sun.jna.Pointer.getString(J)Ljava/lang/String;+5
j  org.freedesktop.gstreamer.lowlevel.GTypeMapper$4.fromNative(Ljava/lang/Object;Lcom/sun/jna/FromNativeContext;)Ljava/lang/Object;+76
j  com.sun.jna.Structure.readField(Lcom/sun/jna/Structure$StructField;)Ljava/lang/Object;+169
j  com.sun.jna.Structure.read()V+90
j  com.sun.jna.Structure.autoRead()V+8
j  com.sun.jna.Function.invoke(Ljava/lang/reflect/Method;[Ljava/lang/Class;Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+380
j  com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+390
j  jdk.proxy2.$Proxy5.g_error_free(Lorg/freedesktop/gstreamer/lowlevel/GstAPI$GErrorStruct;)V+16 jdk.proxy2

Solution

Use raw pointer variant of g_error_free function to prevent reading of a released structure.

[neilcsmith-net]

Thanks for this. Will review.

But this issue should not be occurring. Please open an issue or start a mailing list thread with further details of gst1-java-core, JNA and Java / OS versions. And attach the full hs_err file if you have it.

[denisenkom]

Thank you! Created issue: #280