From 22b9c96b691d3bb5a5d3db510db353b3b2bc2f74 Mon Sep 17 00:00:00 2001
From: Yufeng Wang <yufengwang@google.com>
Date: Thu, 16 May 2024 14:29:31 +0000
Subject: [PATCH] Revert using strncmp instead of strcmp to make the function
 robust and safe from buffer overruns. #33449 (#33482)

* Add tests for Nullable String attribute

* Use strcmp instead of strncmp to compare a null-terminated arg
---
 examples/chip-tool/commands/common/Command.cpp    |  2 +-
 examples/fabric-admin/commands/common/Command.cpp |  2 +-
 src/app/tests/suites/TestCluster.yaml             | 14 +++++++++++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/examples/chip-tool/commands/common/Command.cpp b/examples/chip-tool/commands/common/Command.cpp
index 1dff5e83f666b5..2c4f1eb3540e9f 100644
--- a/examples/chip-tool/commands/common/Command.cpp
+++ b/examples/chip-tool/commands/common/Command.cpp
@@ -171,7 +171,7 @@ bool HandleNullableOptional(Argument & arg, char * argValue, std::function<bool(
     if (arg.isNullable())
     {
         auto * nullable = reinterpret_cast<chip::app::DataModel::Nullable<T> *>(arg.value);
-        if (argValue != nullptr && strncmp(argValue, "null", 4) == 0)
+        if (strcmp(argValue, "null") == 0)
         {
             nullable->SetNull();
             return true;
diff --git a/examples/fabric-admin/commands/common/Command.cpp b/examples/fabric-admin/commands/common/Command.cpp
index 7e5689130e3e97..f0521a9c259a8b 100644
--- a/examples/fabric-admin/commands/common/Command.cpp
+++ b/examples/fabric-admin/commands/common/Command.cpp
@@ -171,7 +171,7 @@ bool HandleNullableOptional(Argument & arg, char * argValue, std::function<bool(
     if (arg.isNullable())
     {
         auto * nullable = reinterpret_cast<chip::app::DataModel::Nullable<T> *>(arg.value);
-        if (argValue != nullptr && strncmp(argValue, "null", 4) == 0)
+        if (strcmp(argValue, "null") == 0)
         {
             nullable->SetNull();
             return true;
diff --git a/src/app/tests/suites/TestCluster.yaml b/src/app/tests/suites/TestCluster.yaml
index 017d6ce6b6daf4..540683a5422f13 100644
--- a/src/app/tests/suites/TestCluster.yaml
+++ b/src/app/tests/suites/TestCluster.yaml
@@ -2896,7 +2896,7 @@ tests:
           constraints:
               notValue: nullableOctetStrTestValue
 
-    # Tests for Char String attribute
+    # Tests for Nullable Char String attribute
 
     - label: "Read attribute NULLABLE_CHAR_STRING Default Value"
       command: "readAttribute"
@@ -2968,6 +2968,18 @@ tests:
       response:
           error: UNSUPPORTED_CLUSTER
 
+    - label: "Write attribute NULLABLE_CHAR_STRING - Value starting with null"
+      command: "writeAttribute"
+      attribute: "nullable_char_string"
+      arguments:
+          value: "nulla"
+
+    - label: "Read attribute NULLABLE_CHAR_STRING"
+      command: "readAttribute"
+      attribute: "nullable_char_string"
+      response:
+          value: "nulla"
+
     # Tests for command with optional arguments
     - label:
           "Send a command that takes an optional parameter but do not set it."