This is a bit of an interesting crash, in that it was a SIGBUS and not a SIGSEGV or SIGABRT like usual. Full backtrace, memmaps, etc. are available in the downstream bug. Truncated backtrace: Thread no. 1 (10 frames) #0 __memcpy_sse2_unaligned at ../sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S:36 #1 IPC::ArgumentDecoder::ArgumentDecoder at /usr/src/debug/webkitgtk-2.10.0/Source/WebKit2/Platform/IPC/ArgumentDecoder.cpp:41 #2 IPC::MessageDecoder::MessageDecoder at /usr/src/debug/webkitgtk-2.10.0/Source/WebKit2/Platform/IPC/MessageDecoder.cpp:49 #3 std::make_unique<IPC::MessageDecoder, IPC::DataReference, WTF::Vector<IPC::Attachment, 0ul, WTF::CrashOnOverflow, 16ul> >(IPC::DataReference&&, WTF::Vector<IPC::Attachment, 0ul, WTF::CrashOnOverflow, 16ul>&&) at /usr/src/debug/webkitgtk-2.10.0/Source/WTF/wtf/StdLibExtras.h:327 #4 IPC::Connection::processMessage at /usr/src/debug/webkitgtk-2.10.0/Source/WebKit2/Platform/IPC/unix/ConnectionUnix.cpp:246 #5 IPC::Connection::readyReadHandler at /usr/src/debug/webkitgtk-2.10.0/Source/WebKit2/Platform/IPC/unix/ConnectionUnix.cpp:356 #6 std::function<void ()>::operator()() const at /usr/include/c++/5.1.1/functional:2271 #7 WTF::WorkQueue::<lambda(GIOCondition)>::operator() at /usr/src/debug/webkitgtk-2.10.0/Source/WTF/wtf/glib/WorkQueueGLib.cpp:98 #8 std::_Function_handler<bool(GIOCondition), WTF::WorkQueue::registerSocketEventHandler(int, std::function<void()>, std::function<void()>)::<lambda(GIOCondition)> >::_M_invoke(const std::_Any_data &, <unknown type in /usr/lib/debug/usr/lib64/libjavascriptcoregtk-4.0.so.18.2.8.debug, CU 0xf107ac8, DIE 0xf10a682>) at /usr/include/c++/5.1.1/functional:1857 #9 std::function<bool (GIOCondition)>::operator()(GIOCondition) const at /usr/include/c++/5.1.1/functional:2271