Application: ktorrent (4.0.5)
KDE Platform Version: 4.6.00 (4.6.0)
Qt Version: 4.7.1
Operating System: Linux 2.6.38-5-generic x86_64
Distribution: Ubuntu Natty (development branch)

-- Information about the crash:
I can't provide very much information about this, sorry. KTorrent crashed randomly, then again shortly after restarting, and it hasn't happened again yet.
I was downloading four torrents and seeding some others. I wasn't doing anything in KTorrent at the time.
Hopefully the backtrace is of more use than this description is. :(

The crash can be reproduced some of the time.

-- Backtrace:
Application: KTorrent (ktorrent), signal: Segmentation fault
[Current thread is 1 (Thread 0x7f3041392780 (LWP 4034))]

Thread 6 (Thread 0x7f302d151700 (LWP 4036)):
#0  0x00007f303d853003 in __poll (fds=<value optimized out>, nfds=<value optimized out>, timeout=<value optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007f303920a180 in ?? () from /lib/libglib-2.0.so.0
#2  0x00007f303920a6a9 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#3  0x00007f303f0dfa96 in QEventDispatcherGlib::processEvents (this=0x1039f70, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:417
#4  0x00007f303f0b3f02 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f303f0b413c in QEventLoop::exec (this=0x7f302d150dd0, flags=...) at kernel/qeventloop.cpp:201
#6  0x00007f303efcb224 in QThread::exec (this=<value optimized out>) at thread/qthread.cpp:490
#7  0x00007f3040f3fcdd in utp::UTPServerThread::run (this=0x101d360) at ../../src/utp/utpserverthread.cpp:44
#8  0x00007f303efcd9de in QThreadPrivate::start (arg=0x101d360) at thread/qthread_unix.cpp:285
#9  0x00007f303a117d8c in start_thread (arg=0x7f302d151700) at pthread_create.c:304
#10 0x00007f303d86017d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 5 (Thread 0x7f302c950700 (LWP 4037)):
#0  0x00007f303d858223 in select () at ../sysdeps/unix/syscall-template.S:82
#1  0x00007f3040f10524 in dht::RPCServerThread::run (this=0x109a450) at ../../src/dht/rpcserver.cpp:107
#2  0x00007f303efcd9de in QThreadPrivate::start (arg=0x109a450) at thread/qthread_unix.cpp:285
#3  0x00007f303a117d8c in start_thread (arg=0x7f302c950700) at pthread_create.c:304
#4  0x00007f303d86017d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 4 (Thread 0x7f3015407700 (LWP 4083)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f303efccb63 in QMutexPrivate::wait (this=0xf3ae10, timeout=-1) at thread/qmutex_unix.cpp:84
#2  0x00007f303efc95e5 in QMutex::lock (this=0x6d60e8) at thread/qmutex.cpp:167
#3  0x00007f3040eb854c in net::DownloadThread::update (this=0xf3ae90) at ../../src/net/downloadthread.cpp:51
#4  0x00007f3040eb8719 in net::NetworkThread::run (this=0xf3ae90) at ../../src/net/networkthread.cpp:48
#5  0x00007f303efcd9de in QThreadPrivate::start (arg=0xf3ae90) at thread/qthread_unix.cpp:285
#6  0x00007f303a117d8c in start_thread (arg=0x7f3015407700) at pthread_create.c:304
#7  0x00007f303d86017d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#8  0x0000000000000000 in ?? ()

Thread 3 (Thread 0x7f3014c06700 (LWP 4084)):
#0  0x00007f303efc94ef in QMutex::lock (this=0x18b3388) at thread/qmutex.cpp:151
#1  0x00007f3040ed2b0e in QMutexLocker (this=<value optimized out>) at /usr/include/qt4/QtCore/qmutex.h:102
#2  bt::PacketWriter::getNumPacketsToWrite (this=<value optimized out>) at ../../src/peer/packetwriter.cpp:307
#3  0x00007f3040ed2b89 in bt::PacketWriter::hasBytesToWrite (this=<value optimized out>) at ../../src/peer/packetwriter.cpp:286
#4  0x00007f3040eb7c5e in bytesReadyToWrite (this=0xf3b910) at ../../src/net/bufferedsocket.h:118
#5  net::UploadThread::waitForSocketsReady (this=0xf3b910) at ../../src/net/uploadthread.cpp:122
#6  0x00007f3040eb7d86 in net::UploadThread::update (this=0xf3b910) at ../../src/net/uploadthread.cpp:45
#7  0x00007f3040eb8719 in net::NetworkThread::run (this=0xf3b910) at ../../src/net/networkthread.cpp:48
#8  0x00007f303efcd9de in QThreadPrivate::start (arg=0xf3b910) at thread/qthread_unix.cpp:285
#9  0x00007f303a117d8c in start_thread (arg=0x7f3014c06700) at pthread_create.c:304
#10 0x00007f303d86017d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7f300ffff700 (LWP 4085)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f303efce09b in wait (this=<value optimized out>, mutex=0x2622730, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:88
#2  QWaitCondition::wait (this=<value optimized out>, mutex=0x2622730, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:160
#3  0x00007f3040ebb102 in net::ReverseResolverThread::run (this=0x2622720) at ../../src/net/reverseresolver.cpp:123
#4  0x00007f303efcd9de in QThreadPrivate::start (arg=0x2622720) at thread/qthread_unix.cpp:285
#5  0x00007f303a117d8c in start_thread (arg=0x7f300ffff700) at pthread_create.c:304
#6  0x00007f303d86017d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#7  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f3041392780 (LWP 4034)):
[KCrash Handler]
#6  __memcpy_sse2 () at ../sysdeps/x86_64/multiarch/../memcpy.S:267
#7  0x00007f303d27b0b6 in QCA::MemoryRegion::MemoryRegion(QByteArray const&) () from /usr/lib/libqca.so.2
#8  0x00007f303d2914c5 in QCA::Hash::update(QByteArray const&) () from /usr/lib/libqca.so.2
#9  0x00007f3040ea40ca in bt::SHA1HashGen::update (this=0x7f3028067220, data=0x7f30413b5d4d "C\264\222\255\336\263\220g\365\020w\f\357X6\327\224\376\334\222,\337R\036\244\277\312TE\374&W\316\355y\330y\364\337\232\371\264\375o\217\344\371\030f\352o\215\062}L\311\246}\025%r\023x\370yK\226\034\264\276\331\212\347\360[\374\326\341\357\363\071\243\063\315\331u\251I\025*\374k\342\061\027\357\214;.\361UU\371u\202\037\351\313\357\350\034\371S\375}D\316\233W6f\\<e\367\315)lQ\376Xg\376Pc\021\030\223\366\260(T\016\177\312\276\246\302\071}y\377\016\206\257\320\262\070\371\234\205bl\236b,\270\216T\356\236\323\243s,\025\360\064*\025o\f\277\366\371!a\357\f&-\301\225o\334\070\367\330\337\312"..., len=16384) at ../../src/util/sha1hashgen.cpp:240
#10 0x00007f3040eda881 in bt::ChunkDownload::updateHash (this=0x7f3028067160) at ../../src/download/chunkdownload.cpp:555
#11 0x00007f3040edc4d7 in bt::ChunkDownload::piece (this=0x7f3028067160, p=..., ok=<value optimized out>) at ../../src/download/chunkdownload.cpp:127
#12 0x00007f3040ee0857 in bt::Downloader::pieceReceived (this=0x12963f0, p=...) at ../../src/download/downloader.cpp:134
#13 0x00007f3040ecad6c in bt::Peer::packetReady (this=0x189e3b0, packet=0x7f30100c8bc0 "\a", len=<value optimized out>) at ../../src/peer/peer.cpp:283
#14 0x00007f3040ed32f8 in bt::PacketReader::update (this=0x1ad1bc0) at ../../src/peer/packetreader.cpp:141
#15 0x00007f3040ec8f35 in bt::Peer::update (this=0x189e3b0) at ../../src/peer/peer.cpp:538
#16 0x00007f3040ecd859 in bt::PeerManager::update (this=0x12754c0) at ../../src/peer/peermanager.cpp:144
#17 0x00007f3040efb4cf in bt::TorrentControl::update (this=0x126e220) at ../../src/torrent/torrentcontrol.cpp:163
#18 0x0000000000429ebd in kt::Core::update (this=0x7f3028004050) at ../../ktorrent/core.cpp:1025
#19 0x0000000000430bc1 in kt::Core::qt_metacall (this=0x7f3028004050, _c=QMetaObject::InvokeMetaMethod, _id=12, _a=0x7fff007da8b0) at ./core.moc:169
#20 0x00007f303f0c9c08 in QMetaObject::activate (sender=0x7f3028004078, m=<value optimized out>, local_signal_index=<value optimized out>, argv=0x0) at kernel/qobject.cpp:3280
#21 0x00007f303f0c87c9 in QObject::event (this=0x7f3028004078, e=<value optimized out>) at kernel/qobject.cpp:1183
#22 0x00007f303e47a5c4 in QApplicationPrivate::notify_helper (this=0xf96ea0, receiver=0x7f3028004078, e=0x7fff007daf90) at kernel/qapplication.cpp:4445
#23 0x00007f303e47eefa in QApplication::notify (this=<value optimized out>, receiver=0x7f3028004078, e=0x7fff007daf90) at kernel/qapplication.cpp:4324
#24 0x0000000000437d91 in kt::App::notify (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>) at ../../ktorrent/app.cpp:97
#25 0x00007f303f0b4b1c in QCoreApplication::notifyInternal (this=0x7fff007db270, receiver=0x7f3028004078, event=0x7fff007daf90) at kernel/qcoreapplication.cpp:732
#26 0x00007f303f0e2542 in sendEvent (this=0xf93170) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:215
#27 QTimerInfoList::activateTimers (this=0xf93170) at kernel/qeventdispatcher_unix.cpp:603
#28 0x00007f303f0df378 in timerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:184
#29 idleTimerSourceDispatch (source=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:231
#30 0x00007f3039209c2d in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#31 0x00007f303920a418 in ?? () from /lib/libglib-2.0.so.0
#32 0x00007f303920a6a9 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#33 0x00007f303f0dfa3f in QEventDispatcherGlib::processEvents (this=0xf32250, flags=<value optimized out>) at kernel/qeventdispatcher_glib.cpp:415
#34 0x00007f303e520f0e in QGuiEventDispatcherGlib::processEvents (this=<value optimized out>, flags=<value optimized out>) at kernel/qguieventdispatcher_glib.cpp:204
#35 0x00007f303f0b3f02 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#36 0x00007f303f0b413c in QEventLoop::exec (this=0x7fff007db200, flags=...) at kernel/qeventloop.cpp:201
#37 0x00007f303f0b854b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1009
#38 0x00000000004271ef in main (argc=1, argv=0x7fff007dc028) at ../../ktorrent/main.cpp:176

Reported using DrKonqi