From 7381d7635789a87d9a37b105838be5ee797c21d0 Mon Sep 17 00:00:00 2001
From: Junior Martinez <67972863+jmartinez-silabs@users.noreply.github.com>
Date: Sat, 6 Jan 2024 18:42:48 -0500
Subject: [PATCH] [Silabs]Add a static assert to ensure there is no out of
 bound write (#31268)

* Add a static assert to ensure there is no out of bound write

* address comments
---
 src/platform/silabs/BLEManagerImpl.h          | 5 ++++-
 src/platform/silabs/efr32/BLEManagerImpl.cpp  | 1 +
 src/platform/silabs/rs911x/BLEManagerImpl.cpp | 1 +
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/platform/silabs/BLEManagerImpl.h b/src/platform/silabs/BLEManagerImpl.h
index de149d7d71149b..72cca87af37351 100644
--- a/src/platform/silabs/BLEManagerImpl.h
+++ b/src/platform/silabs/BLEManagerImpl.h
@@ -143,7 +143,6 @@ class BLEManagerImpl final : public BLEManager, private BleLayer, private BlePla
     static BLEManagerImpl sInstance;
 
     // ===== Private members reserved for use by this class only.
-
     enum class Flags : uint16_t
     {
         kAdvertisingEnabled     = 0x0001,
@@ -161,6 +160,10 @@ class BLEManagerImpl final : public BLEManager, private BleLayer, private BlePla
         kUnusedIndex         = 0xFF,
     };
 
+    static constexpr uint8_t kFlagTlvSize       = 3; // 1 byte for length, 1b for type and 1b for the Flag value
+    static constexpr uint8_t kUUIDTlvSize       = 4; // 1 byte for length, 1b for type and 2b for the UUID value
+    static constexpr uint8_t kDeviceNameTlvSize = (2 + kMaxDeviceNameLength); // 1 byte for length, 1b for type and + device name
+
     struct CHIPoBLEConState
     {
 #if !(SLI_SI91X_ENABLE_BLE || RSI_BLE_ENABLE)
diff --git a/src/platform/silabs/efr32/BLEManagerImpl.cpp b/src/platform/silabs/efr32/BLEManagerImpl.cpp
index fe8acb3ad02fcb..0cc4ae0d6c54ec 100644
--- a/src/platform/silabs/efr32/BLEManagerImpl.cpp
+++ b/src/platform/silabs/efr32/BLEManagerImpl.cpp
@@ -444,6 +444,7 @@ CHIP_ERROR BLEManagerImpl::ConfigureAdvertisingData(void)
 
     mDeviceNameLength = strlen(mDeviceName); // Device Name length + length field
     VerifyOrExit(mDeviceNameLength < kMaxDeviceNameLength, err = CHIP_ERROR_INVALID_ARGUMENT);
+    static_assert((kUUIDTlvSize + kDeviceNameTlvSize) <= MAX_RESPONSE_DATA_LEN, "Scan Response buffer is too small");
 
     mDeviceIdInfoLength = sizeof(mDeviceIdInfo); // Servicedatalen + length+ UUID (Short)
     static_assert(sizeof(mDeviceIdInfo) + CHIP_ADV_SHORT_UUID_LEN + 1 <= UINT8_MAX, "Our length won't fit in a uint8_t");
diff --git a/src/platform/silabs/rs911x/BLEManagerImpl.cpp b/src/platform/silabs/rs911x/BLEManagerImpl.cpp
index 717f0798c2068d..343acf6f50ac84 100644
--- a/src/platform/silabs/rs911x/BLEManagerImpl.cpp
+++ b/src/platform/silabs/rs911x/BLEManagerImpl.cpp
@@ -563,6 +563,7 @@ CHIP_ERROR BLEManagerImpl::ConfigureAdvertisingData(void)
 
     mDeviceNameLength = strlen(mDeviceName); // Device Name length + length field
     VerifyOrExit(mDeviceNameLength < kMaxDeviceNameLength, err = CHIP_ERROR_INVALID_ARGUMENT);
+    static_assert((kFlagTlvSize + kUUIDTlvSize + kDeviceNameTlvSize) <= MAX_RESPONSE_DATA_LEN, "Scan Response buffer is too small");
 
     mDeviceIdInfoLength = sizeof(mDeviceIdInfo); // Servicedatalen + length+ UUID (Short)
     static_assert(sizeof(mDeviceIdInfo) + CHIP_ADV_SHORT_UUID_LEN + 1 <= UINT8_MAX, "Our length won't fit in a uint8_t");