Add a nv-egl-crashy-query-device-attrib workaround.

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -161,6 +161,14 @@ const char* KnownWorkarounds[]{
    possible to get driver version through EGL, so enabling this unconditionally
    on all EGL NV contexts. */
 "nv-egl-incorrect-gl11-function-pointers",
+
+/* On NV driver 450.80.02, eglQueryDeviceAttribEXT() segfaults when querying
+   GPUs that the user does not have access to (i.e. via cgroup). Instead,
+   always call eglQueryDeviceStringEXT() as that doesn't segfault and sets an
+   error that can be retrieved via eglGetError() to see if the user has access
+   to that device. On well-behaved driver versions, eglQueryDeviceAttribEXT()
+   returns false instead of segfaulting. */
+"nv-egl-crashy-query-device-attrib",
 #endif
 
 #ifndef MAGNUM_TARGET_GLES

src/Magnum/Platform/WindowlessEglApplication.cpp

@@ -180,8 +180,20 @@ WindowlessEglContext::WindowlessEglContext(const Configuration& configuration, G
                 /* Go through the EGL devices and find one that has the desired
                    CUDA device number */
                 for(selectedDevice = 0; selectedDevice < UnsignedInt(count); ++selectedDevice) {
+                    /* On NV driver 450.80.02, eglQueryDeviceAttribEXT()
+                       segfaults when querying GPUs that the user does not have
+                       access to (i.e. via cgroup). Instead, always call
+                       eglQueryDeviceStringEXT() as that doesn't segfault and
+                       sets an error that can be retrieved via eglGetError() to
+                       see if the user has access to that device. On
+                       well-behaved driver versions, eglQueryDeviceAttribEXT()
+                       returns false instead of segfaulting. */
+                    const char* const eglExtensions = eglQueryDeviceStringEXT(devices[selectedDevice], EGL_EXTENSIONS);
+                    if(eglGetError() == EGL_BAD_DEVICE_EXT && !magnumContext->isDriverWorkaroundDisabled("nv-egl-crashy-query-device-attrib"))
+                        continue;
+
                     if(magnumContext && (magnumContext->internalFlags() >= GL::Context::InternalFlag::DisplayVerboseInitializationLog))
-                        Debug{} << "Platform::WindowlessEglApplication: eglQueryDeviceStringEXT(EGLDevice=" << Debug::nospace << selectedDevice << Debug::nospace << "):" << eglQueryDeviceStringEXT(devices[selectedDevice], EGL_EXTENSIONS);
+                        Debug{} << "Platform::WindowlessEglApplication: eglQueryDeviceStringEXT(EGLDevice=" << Debug::nospace << selectedDevice << Debug::nospace << "):" << eglExtensions;
 
                     EGLAttrib cudaDeviceNumber;
                     if(eglQueryDeviceAttribEXT(devices[selectedDevice], EGL_CUDA_DEVICE_NV, &cudaDeviceNumber) && UnsignedInt(cudaDeviceNumber) == configuration.cudaDevice())