From 269ce85b855119cb6afbd0a9d3e122470966def0 Mon Sep 17 00:00:00 2001
From: Boris Zbarsky <bzbarsky@apple.com>
Date: Wed, 31 Aug 2022 19:58:35 -0400
Subject: [PATCH] Fix endpoint index lookups to handle invalid endpoint ids
 correctly. (#22275)

There are some code paths that loop over all endpoint indices (including ones
that do not have an endpoint defined yet) and then use the endpoint id to look
up endpoint indices.  Make sure we don't claim an endpoint index for the "not an
endpoint" endpoint id.

Also fixes findClusterEndpointIndex to check for the invalid endpoint id before
working with it, since that means the endpoint index it's looking at does not
correspond to a defined endpoint.

Fixes https://github.com/project-chip/connectedhomeip/issues/22272
---
 src/app/util/attribute-storage.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/app/util/attribute-storage.cpp b/src/app/util/attribute-storage.cpp
index 7e8bad31264561..26740c922ec2bf 100644
--- a/src/app/util/attribute-storage.cpp
+++ b/src/app/util/attribute-storage.cpp
@@ -187,6 +187,11 @@ void emberAfSetDynamicEndpointCount(uint16_t dynamicEndpointCount)
 
 uint16_t emberAfGetDynamicIndexFromEndpoint(EndpointId id)
 {
+    if (id == kInvalidEndpointId)
+    {
+        return kEmberInvalidEndpointIndex;
+    }
+
     uint16_t index;
     for (index = FIXED_ENDPOINT_COUNT; index < MAX_ENDPOINT_COUNT; index++)
     {
@@ -831,6 +836,11 @@ static uint16_t findClusterEndpointIndex(EndpointId endpoint, ClusterId clusterI
         {
             break;
         }
+        if (emAfEndpoints[i].endpoint == kInvalidEndpointId)
+        {
+            // Not actually a configured endpoint.
+            continue;
+        }
         epi = static_cast<uint16_t>(
             epi + ((emberAfFindClusterIncludingDisabledEndpoints(emAfEndpoints[i].endpoint, clusterId, mask) != nullptr) ? 1 : 0));
     }
@@ -840,6 +850,11 @@ static uint16_t findClusterEndpointIndex(EndpointId endpoint, ClusterId clusterI
 
 static uint16_t findIndexFromEndpoint(EndpointId endpoint, bool ignoreDisabledEndpoints)
 {
+    if (endpoint == kInvalidEndpointId)
+    {
+        return kEmberInvalidEndpointIndex;
+    }
+
     uint16_t epi;
     for (epi = 0; epi < emberAfEndpointCount(); epi++)
     {