Bug 228234 – [GTK] Uninitialized data in UIClient::windowFrame written over IPC

• Status: NEW
• Component: WebKitGTK

[Michael Catanzaro]

==87186== Thread 55 ReceiveQueue:
==87186== Syscall param sendmsg(msg.msg_iov[1]) points to uninitialised byte(s)
==87186==    at 0x59A0ACD: sendmsg (in /usr/lib64/libc-2.33.so)
==87186==    by 0x6AC8783: IPC::Connection::sendOutputMessage(IPC::UnixMessage&) (ConnectionUnix.cpp:536)
==87186==    by 0x6ACA719: IPC::Connection::sendOutgoingMessage(WTF::UniqueRef<IPC::Encoder>&&) (ConnectionUnix.cpp:454)
==87186==    by 0x6AB7997: IPC::Connection::sendOutgoingMessages() [clone .part.0] (Connection.cpp:932)
==87186==    by 0xA9C8505: operator() (Function.h:82)
==87186==    by 0xA9C8505: WTF::RunLoop::performWork() (RunLoop.cpp:133)
==87186==    by 0xAA1D8F8: operator() (RunLoopGLib.cpp:80)
==87186==    by 0xAA1D8F8: WTF::RunLoop::RunLoop()::{lambda(void*)#1}::_FUN(void*) (RunLoopGLib.cpp:82)
==87186==    by 0xAA1E22E: operator() (RunLoopGLib.cpp:53)
==87186==    by 0xAA1E22E: WTF::RunLoop::{lambda(_GSource*, int (*)(void*), void*)#1}::_FUN(_GSource*, int (*)(void*), void*) (RunLoopGLib.cpp:56)
==87186==    by 0x5609922: g_main_dispatch (gmain.c:3344)
==87186==    by 0x560A875: g_main_context_dispatch (gmain.c:4062)
==87186==    by 0x560AA61: g_main_context_iterate (gmain.c:4138)
==87186==    by 0x560AEFE: g_main_loop_run (gmain.c:4336)
==87186==    by 0xAA1E34F: WTF::RunLoop::run() (RunLoopGLib.cpp:108)
==87186==  Address 0x21525daa is in a rw- anonymous segment
==87186==  Uninitialised value was created by a stack allocation
==87186==    at 0x6C310A0: UIClient::windowFrame(WebKit::WebPageProxy&, WTF::Function<void (WebCore::FloatRect)>&&) (WebKitUIClient.cpp:240)

[Carlos Garcia Campos]

I guess the stack allocation at UIClient::windowFrame is the GdkRectangle, but it's initialized:

GdkRectangle geometry = { 0, 0, 0, 0 };

It could be the default geometry, which is not initialized but it's always set by webkit_window_properties_get_geometry().

[Michael Catanzaro]

> It could be the default geometry, which is not initialized but it's always
> set by webkit_window_properties_get_geometry().

webkit_window_properties_get_geometry() copies windowProperties->priv->geometry, so that would mean this would have to somehow be uninitialized. But that seems impossible, because the entire priv struct should be zero-initialized.

I don't see the problem either....