Fix ConcurrentModificationException in client-registration policy reads#50969
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The client-registration policies read their configuration with ComponentModel.getConfig().getList(key), which lazily inserts the key when it is absent. The ComponentModel is cached and shared across request threads, so concurrent dynamic client registrations structurally modify the same HashMap and one throws ConcurrentModificationException. Read the config the same non-mutating way as the rest of the codebase, getConfig().getOrDefault(key, emptyList()), which keeps the empty-on-absent contract getList provided and removes the mutation. Applied to the TrustedHost, ClientScopes, ProtocolMappers and WebOrigins policies. Closes keycloak#50286 Signed-off-by: Michael Stingl <mail@michaelstingl.com> Signed-off-by: Alexander Schwartz <alexander.schwartz@ibm.com> Co-authored-by: Alexander Schwartz <alexander.schwartz@ibm.com>
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@pruivo - please review when you have the time. Thanks! |
Unreported flaky test detectedIf the flaky tests below are affected by the changes, please review and update the changes accordingly. Otherwise, a maintainer should report the flaky tests prior to merging the PR. org.keycloak.testsuite.adapter.servlet.SAMLServletAdapterTest#salesPostSigTransientTestKeycloak CI - Adapter IT Strict Cookies |
pruivo
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Jul 17, 2026
| if (allowedScopesConfig != null) { | ||
| allAllowed.addAll(allowedScopesConfig); | ||
| } | ||
| List<String> allowedScopesConfig = componentModel.getConfig().getOrDefault(ClientScopesClientRegistrationPolicyFactory.ALLOWED_CLIENT_SCOPES, Collections.emptyList()); |
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@ahus1 this changes the semantics. Is this ok?
getList- if the key does not exist, it creates a list, stores in the map, and keeps track of anything added to the list.getOrDefault- if the key does not exist, it returns an unmodifiable list id
pruivo
reviewed
Jul 17, 2026
| public void validateConfiguration(KeycloakSession session, RealmModel realm, ComponentModel config) throws ComponentValidationException { | ||
| List<String> allowedScopesConfig = config.getConfig().getList(ClientScopesClientRegistrationPolicyFactory.ALLOWED_CLIENT_SCOPES); | ||
| List<String> allowedScopesConfig = config.getConfig().getOrDefault(ClientScopesClientRegistrationPolicyFactory.ALLOWED_CLIENT_SCOPES, Collections.emptyList()); | ||
| if (!getClientScopes(session).containsAll(allowedScopesConfig)) { |
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getClientScopes(session).containsAll(allowedScopesConfig) is a O(N*M) complexity, where N is the size of getClientScopes list and M the size of allowedScopesConfig.
It may be problematic if these lists are large.
pruivo
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Jul 17, 2026
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Since this is a backport, I'm ok to approve it as is.
ahus1
enabled auto-merge (squash)
July 17, 2026 18:54
rmartinc
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Jul 20, 2026
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The client-registration policies read their configuration with ComponentModel.getConfig().getList(key), which lazily inserts the key when it is absent. The ComponentModel is cached and shared across request threads, so concurrent dynamic client registrations structurally modify the same HashMap and one throws ConcurrentModificationException.
Read the config the same non-mutating way as the rest of the codebase, getConfig().getOrDefault(key, emptyList()), which keeps the empty-on-absent contract getList provided and removes the mutation. Applied to the TrustedHost, ClientScopes, ProtocolMappers and WebOrigins policies.
Closes #50286