78:T1adb, ## Description Sunshine randomly crashes when a second client connects while another one is already streaming. It doesn't happen on every connect (about one in three in my case), but when it does, every client's stream drops at once. Seen on Linux with NVENC and wlr capture (headless labwc, NVIDIA 615.x). The only trace is in the kernel log: ``` kernel: session::video[...]: segfault at 0 ip 0000000000000000 sp ... error 14 ``` The cause is that `cuda::init()` reloads the shared CUDA function table (`cdf`) on every call, and every new stream calls it when it creates its encode device. `cuda_load_functions()` frees the current table, installs a zeroed one, and only then opens `libcuda.so.1` and fills the entries in. A stream that is already encoding calls through `cdf` on every frame. If it does so inside that window, it calls a null function pointer and the whole process dies. Backtrace from the core dump (v2026.914.233613; `master` has the same `init()`): ``` Thread 1 (the stream already running) #0 0x0000000000000000 in ?? () #1 cuda::gl_cuda_vram_t::convert(platf::img_t&) () <- call *0x278(%rax), rax = freshly zeroed table #2 stream::videoThread(stream::session_t*) () Thread 15 (the stream that just started) #1 _dl_lookup_map (name="libcuda.so.1") #7 dlopen #8 cuda::init() () #9 cuda::make_avcodec_gl_encode_device(int, int, int, int) () #10 wl::wlr_vram_t::make_avcodec_encode_device(platf::pix_fmt_e) () #11 video::make_encode_device(...) () #12 stream::videoThread(stream::session_t*) () ``` This change loads the table once and keeps it for the life of the process. Later calls only run `cuInit(0)` again, so a first load that failed is still retried. A mutex stops streams that start at the same time from loading it concurrently. To test this without a GPU, `cuda::init()` now hands the table and the loader to an `init(table, load)` overload, the same way `device_pci_bus_id()` takes its driver operations. ### Screenshot ### Issues Fixed or Closed #### Roadmap Issues ## Testing I first made the crash reproducible on demand, so it happened on every attempt instead of about one connect in three. Then I applied the fix, rebuilt Sunshine, and ran it on the same machine. The end-to-end tests with the fix were clean: no crashes, and both streams kept running. The crash happened every time before the fix and never after it, which confirms the fix resolves it. The details are below. **Regression tests** in `tests/unit/platform/linux/test_cuda.cpp`. They use a fake loader, so they need no GPU and run in CI: - `CudaInitTest.LoadsTheFunctionTableOnlyOnce`: a second `init()` must not load the table again. It fails on the first commit (the table is loaded twice) and passes with the fix, in 20 out of 20 repeats each. - `CudaInitTest.RetriesLoadingAfterAFailure`: a load that failed is retried on the next call. It passes on both commits. Full `test_sunshine` suite, in a Fedora 44 container: 862 passed and 1 failed (the test above) on the first commit, and 863 passed with the fix. 14 tests were skipped in both runs. **Against the real driver** (Fedora 44, RTX 3050, driver 615.71.10): a manual check, not part of this PR, intercepted `dlopen("libcuda.so.1")` during a second `init()`. Without the fix, the entry every frame conversion calls first (`cuGraphicsMapResources`) was null in 30 out of 30 runs. **End to end:** headless labwc, wlr capture, NVENC, with one client streaming continuously. A preloaded shim delayed `dlopen("libcuda.so.1")` by 100 ms to widen the window: - without the fix: a second client connected 3 times, and all 3 crashed Sunshine with the segfault above - with this PR: a second client connected 7 times, with no crashes, and both streams kept running Built with `BUILD_WERROR=ON` (gcc 15, CUDA 13.1.1). `clang-format` reports no changes. Not run: CI, Windows and macOS (the change is Linux-only). ## Type of Change - [ ] **feat**: New feature (non-breaking change which adds functionality) - [x] **fix**: Bug fix (non-breaking change which fixes an issue) - [ ] **docs**: Documentation only changes - [ ] **style**: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.) - [ ] **refactor**: Code change that neither fixes a bug nor adds a feature - [ ] **perf**: Code change that improves performance - [x] **test**: Adding missing tests or correcting existing tests - [ ] **build**: Changes that affect the build system or external dependencies - [ ] **ci**: Changes to CI configuration files and scripts - [ ] **chore**: Other changes that don't modify src or test files - [ ] **revert**: Reverts a previous commit - [ ] **BREAKING CHANGE**: Introduces a breaking change (can be combined with any type above) ## Checklist - [x] Code follows the style guidelines of this project - [x] Code has been self-reviewed - [x] Code has been commented, particularly in hard-to-understand areas - [x] Code docstring/documentation-blocks for new or existing methods/components have been added or updated - [x] Tests have been added or updated for new or modified functionality, including regression tests for bug fixes ### AI Usage See our [AI usage policy](https://docs.lizardbyte.dev/latest/developers/contributing.html#ai-usage). - [x] AI tools were used while preparing this PR Claude helped read the core dump, write the test and the fix, and run the verification described above. 79:Tc09,## [![Quality Gate Passed](https://cdn.trylle.com/media/images/9c421b538b25f3b09f4b2fe2b0372ec2?key=AcQi5aACo4g%2FYo5l5IjHF3xVl6%2FNs4GJqvnQmK1WYQSdtSdRF26f%2FHvQaxVtYfwO5Zmn8dluvsUfc7rMx%2B%2FgQY2OVykvJejXvd9AGYYByqXGzgFAz8gNAGxDHrnoHKtqik9jZGG8QAdOiWU9mFubBHZXaF9DzWU0BmQyy0MI3IUIg8dPDcYRSwg1fpo1NafBvh5XrY6twS%2B7azc0BlfnOuF%2F1fUWs5kIgW%2Fyqnll0eMqf1%2BqbdHuUxive7nB4cFYbX1HRO8%3D "Quality Gate Passed")](https://sonarcloud.io/dashboard?id=LizardByte_Sunshine&pullRequest=6014) **Quality Gate passed** Issues\ ![](https://cdn.trylle.com/media/images/1f80bcb90d79b2b11bb739f48a001eba?key=AUC4JpfjThVa%2Bs177EUoO7i8HgbzCRl8Z01fv0xPDZPLrH%2BDQmUptp2xqyXz6Ry5UVz15ge3hfUJfcrNsco49HOerENB6eluOhBp2S6N6eD%2BR8aS31oqgsuMjumS%2FmD8yI8EO6a6pU6kCSlBJSXMdzHQdpi2f29zd6J3eWkDgK27I67k4Q%2FGj8yrJg24QPoLAitYTBYgMAOhTN%2FUCC%2FmZ0m0c0v6pN10QUhZhOgt%2BmAQ "") [0 New issues](https://sonarcloud.io/project/issues?id=LizardByte_Sunshine&pullRequest=6014&issueStatuses=OPEN,CONFIRMED&sinceLeakPeriod=true)\ ![](https://cdn.trylle.com/media/images/2dc6921822f23cc8f5227994feb4f3a1?key=Ac0A%2B0GOiKtG7s6yUOkdAw93Omn2d6UW4CeD2L0U%2BJBRKNXLhiTbhcAYui4CWhVpOt5sS%2FIpI5GuMUAr%2BR7rVdKH%2BhxG6gKozNa21fwbQxSdpTU%2FjZ2iFl9kDiolBU4S%2BRFIeFGghV92lOKfCd6%2BYiGPTNPcoNmsgSbkTS3%2FbidmrAdQOrK9LWMRC%2FNHb3Q89TG%2B6T73DUYy9yDpnhpnR17g1F78itSkkEQd60W2pU9pWj4%3D "") [0 Accepted issues](https://sonarcloud.io/project/issues?id=LizardByte_Sunshine&pullRequest=6014&issueStatuses=ACCEPTED) Measures\ ![](https://cdn.trylle.com/media/images/1f80bcb90d79b2b11bb739f48a001eba?key=AUC4JpfjThVa%2Bs177EUoO7i8HgbzCRl8Z01fv0xPDZPLrH%2BDQmUptp2xqyXz6Ry5UVz15ge3hfUJfcrNsco49HOerENB6eluOhBp2S6N6eD%2BR8aS31oqgsuMjumS%2FmD8yI8EO6a6pU6kCSlBJSXMdzHQdpi2f29zd6J3eWkDgK27I67k4Q%2FGj8yrJg24QPoLAitYTBYgMAOhTN%2FUCC%2FmZ0m0c0v6pN10QUhZhOgt%2BmAQ "") [0 Security Hotspots](https://sonarcloud.io/project/security_hotspots?id=LizardByte_Sunshine&pullRequest=6014&issueStatuses=OPEN,CONFIRMED&sinceLeakPeriod=true)\ ![](https://cdn.trylle.com/media/images/1f80bcb90d79b2b11bb739f48a001eba?key=AUC4JpfjThVa%2Bs177EUoO7i8HgbzCRl8Z01fv0xPDZPLrH%2BDQmUptp2xqyXz6Ry5UVz15ge3hfUJfcrNsco49HOerENB6eluOhBp2S6N6eD%2BR8aS31oqgsuMjumS%2FmD8yI8EO6a6pU6kCSlBJSXMdzHQdpi2f29zd6J3eWkDgK27I67k4Q%2FGj8yrJg24QPoLAitYTBYgMAOhTN%2FUCC%2FmZ0m0c0v6pN10QUhZhOgt%2BmAQ "") [0.0% Coverage on New Code](https://sonarcloud.io/component_measures?id=LizardByte_Sunshine&pullRequest=6014&metric=new_coverage&view=list)\ ![](https://cdn.trylle.com/media/images/1f80bcb90d79b2b11bb739f48a001eba?key=AUC4JpfjThVa%2Bs177EUoO7i8HgbzCRl8Z01fv0xPDZPLrH%2BDQmUptp2xqyXz6Ry5UVz15ge3hfUJfcrNsco49HOerENB6eluOhBp2S6N6eD%2BR8aS31oqgsuMjumS%2FmD8yI8EO6a6pU6kCSlBJSXMdzHQdpi2f29zd6J3eWkDgK27I67k4Q%2FGj8yrJg24QPoLAitYTBYgMAOhTN%2FUCC%2FmZ0m0c0v6pN10QUhZhOgt%2BmAQ "") [0.0% Duplication on New Code](https://sonarcloud.io/component_measures?id=LizardByte_Sunshine&pullRequest=6014&metric=new_duplicated_lines_density&view=list) [See analysis details on SonarQube Cloud](https://sonarcloud.io/dashboard?id=LizardByte_Sunshine&pullRequest=6014) 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load the CUDA function table only once\n\ncuda::init() reloaded the shared CUDA function table on every call, and\nevery new stream calls it. Reloading empties the table before filling it\nagain, so a stream already encoding through it could call a null function\npointer, crashing Sunshine when a second client connected.\n\nLoad the table only when it is not loaded yet, and keep it for the life of\nthe process. Later calls only run cuInit again, so a first load that failed\nis still retried. A mutex stops streams that start at the same time from\nloading it concurrently.\n","createdAt":"2026-10-29T23:44:14-03:00","author":{"avatarUrl":"","login":"","name":"Daniel Pereira","type":"User","url":""},"verification":{"verified":false,"reason":"gpg.error.no_gpg_keys_found"}},{"sha":"2f0a679c5ae79a90c87cf2555765fc04b62688b1","message":"test(linux): check that the CUDA function table is loaded only once\n\nEvery stream that starts calls cuda::init(), which reloads the table of\nCUDA driver functions that every encode device shares. The loader empties\nthe table before filling it in again, so a stream already encoding through\nit can call a null function pointer and take the whole process down. On\nLinux with NVENC this crashes Sunshine at random when a second client\nconnects while another one is streaming.\n\ncuda::init() now hands the table and the loader to an overload, the way\ndevice_pci_bus_id() takes its driver operations, so tests can use a fake\nloader and need no GPU. One test checks that a second init() does not load\nthe table again; it fails until the next commit. 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Commits on Fri, Oct 30, 2026