Fix OOB access in LSET when opening a PCB file or updating from schematic.

Fixes https://gitlab.com/kicad/code/kicad/-/issues/18422

common/lset.cpp

@@ -41,14 +41,15 @@
 
 
 LSET::LSET( std::initializer_list<PCB_LAYER_ID> aList ) :
-    BASE_SET()
+    LSET()
 {
     for( PCB_LAYER_ID layer : aList )
         set( layer );
 }
 
 
-LSET::LSET( const LSEQ& aSeq )
+LSET::LSET( const LSEQ& aSeq ) :
+    LSET()
 {
     for( PCB_LAYER_ID layer : aSeq )
         set( layer );

include/base_set.h

@@ -42,7 +42,7 @@ public:
     using iterator = std::vector<int>::iterator;
     using const_iterator = std::vector<int>::const_iterator;
 
-    BASE_SET( size_t size = 64 ) : m_bits( size, 0 ) {}
+    BASE_SET( size_t size ) : m_bits( size, 0 ) {}
 
     bool test( size_t pos ) const
     {
@@ -173,6 +173,8 @@ public:
     // Boolean operators
     BASE_SET& operator&=( const BASE_SET& rhs )
     {
+        assert( m_bits.size() == rhs.m_bits.size() );
+
         for( size_t i = 0; i < m_bits.size(); ++i )
             m_bits[i] &= rhs.m_bits[i];
 
@@ -181,6 +183,8 @@ public:
 
     BASE_SET& operator|=( const BASE_SET& rhs )
     {
+        assert( m_bits.size() == rhs.m_bits.size() );
+
         for( size_t i = 0; i < m_bits.size(); ++i )
             m_bits[i] |= rhs.m_bits[i];
 
@@ -189,6 +193,8 @@ public:
 
     BASE_SET& operator^=( const BASE_SET& rhs )
     {
+        assert( m_bits.size() == rhs.m_bits.size() );
+
         for( size_t i = 0; i < m_bits.size(); ++i )
             m_bits[i] ^= rhs.m_bits[i];
 

include/lset.h

@@ -49,7 +49,7 @@ public:
      * Create an empty (cleared) set.
      */
     LSET() :
-        BASE_SET(PCB_LAYER_ID_COUNT)  // all bits are set to zero in BASE_SET()
+        BASE_SET( PCB_LAYER_ID_COUNT )  // all bits are set to zero in BASE_SET()
     {
     }
 
@@ -59,7 +59,7 @@ public:
     }
 
     LSET( PCB_LAYER_ID aLayer ) :
-        BASE_SET(PCB_LAYER_ID_COUNT)
+        BASE_SET( PCB_LAYER_ID_COUNT )
     {
         set( aLayer );
     }

qa/tests/common/test_lset.cpp

@@ -38,7 +38,7 @@ BOOST_AUTO_TEST_CASE(LSETConstructorEmpty)
 // Initialize LSET from another BASE_SET
 BOOST_AUTO_TEST_CASE(LSETConstructorFromBaseSet)
 {
-    BASE_SET base;
+    BASE_SET base( PCB_LAYER_ID_COUNT );
     base.set(F_Cu);
     base.set(In1_Cu);