Quis custodiet ipsos custodes? LSAN reports a number of OggReporter leaks in M1 that look like the following: Direct leak of 147456 byte(s) in 9 object(s) allocated from: #0 0x446395 in malloc /builds/slave/moz-toolchain/src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:74 #1 0x7f4cee97b68a in OggReporter::Alloc(unsigned long) /builds/slave/try-l64-asan-00000000000000000/build/xpcom/build/nsXPComInit.cpp:419 #2 0x7f4cf4be041c in ogg_stream_init /builds/slave/try-l64-asan-00000000000000000/build/media/libogg/src/ogg_framing.c:194 #3 0x7f4cf2969399 in Init /builds/slave/try-l64-asan-00000000000000000/build/content/media/ogg/OggWriter.cpp:34 #4 0x7f4cf2969399 in mozilla::OggWriter::OggWriter() /builds/slave/try-l64-asan-00000000000000000/build/content/media/ogg/OggWriter.cpp:20 #5 0x7f4cf2931a87 in mozilla::MediaEncoder::CreateEncoder(nsAString_internal const&, unsigned char) /builds/slave/try-l64-asan-00000000000000000/build/content/media/encoder/MediaEncoder.cpp:131 It is a few hundred KB in total.

Is this a new leak? Or is this an old leak that hadn't been analyzed before OggReporter showed up?

I've only started running LSAN recently, if that's what you mean. I didn't notice it at first because I only recently started turning on frame pointers, and before that it was showing up with this useless stack: Direct leak of 114688 byte(s) in 7 object(s) allocated from: #0 0x446395 in malloc /whatever/src/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:74 #1 0x7fdd069c60a8 in ogg_stream_init /somepath/media/libogg/src/ogg_framing.c:194 As for how we could be leaking an ISupports class without any indication in the XPCOM leak checker, see bug 982072 for a theory.

This stack doesn't show us leaking OggReporter. It shows allocations done by OggReporter that are leaking. OggReporter is just a wrapper class around malloc/calloc/realloc/free so that we can identify what libogg is allocating and keep track of it.

Ah, right, my mistake. So I guess this is just libogg leaking some memory.

Running LSAN locally, I got more complete stacks. This is happening under mozilla::DOMMediaStream::CheckTracksAvailable.

This patch is the minimum necessary; currently running through Try to see whether it works correctly...Andrew, can you run it through your setup to see if it fixes the leak?

Comment on attachment 8389317 [details] [diff] [review] fix OggWriter memory leak That gives me this: ==6828==ERROR: AddressSanitizer: attempting to call malloc_usable_size() for pointer which is not owned: 0x615000418018 #0 0x441225 in malloc (/home/amccreight/ff-dbg-asan/dist/bin/firefox+0x441225) #1 0x7f4acf42fddd in malloc_usable_size (/home/amccreight/ff-dbg-asan/dist/bin/libxul.so+0x132addd) #2 0x7f4ad355fe5e in OggReporter::Free(void*) /home/amccreight/mc/xpcom/build/nsXPComInit.cpp:446 #3 0x7f4ad1e5129e in ogg_stream_destroy /home/amccreight/mc/media/libogg/src/ogg_framing.c:231 #4 0x7f4ad1e5123d in mozilla::OggWriter::~OggWriter() /home/amccreight/mc/content/media/ogg/OggWriter.cpp:28 #5 0x7f4ad1e356ad in mozilla::OggWriter::~OggWriter() /home/amccreight/mc/content/media/ogg/OggWriter.cpp:26 #6 0x7f4ad007cd7b in mozilla::MediaEncoder::~MediaEncoder() /home/amccreight/mc/content/media/encoder/MediaEncoder.h:73 #7 0x7f4ad1dfc79b in mozilla::MediaStreamListener::Release() /home/amccreight/ff-dbg-asan/content/media/webspeech/recognition/../../../../dist/include/MediaStreamGraph.h:95 #8 0x7f4ad1dfc811 in mozilla::MediaStream::RemoveAllListenersImpl() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:1783 #9 0x7f4ad1dfe1b5 in mozilla::MediaStream::DestroyImpl() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:1790 #10 0x7f4ad1e080b9 in mozilla::ProcessedMediaStream::DestroyImpl() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:2437 #11 0x7f4ad1dfa1a5 in mozilla::MediaStream::Destroy()::Message::Run() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:1812 #12 0x7f4ad1e08592 in mozilla::MediaStreamGraphImpl::RunThread() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:1182 #13 0x7f4acf506145 in mozilla::(anonymous namespace)::MediaStreamGraphInitThreadRunnable::Run() /home/amccreight/mc/content/media/MediaStreamGraph.cpp:1397

Aha, one should be using ogg_stream_clear instead of ogg_stream_destroy.

Better patch. Andrew, WDYT about this?

Comment on attachment 8389358 [details] [diff] [review] fix OggWriter memory leak Yep, that gets rid of this leak.