Add check for incorrect section/segment entry size

.gitignore

@@ -43,6 +43,7 @@ tests/elf_examples/test_symbols_order.elf
 tests/elf_examples/zavl_gen.ko
 
 tests/elfio_fuzzer
+tests/corpus
 
 examples/writer/hello_x86_64
 examples/write_obj/hello

.vscode/launch.json

@@ -102,7 +102,7 @@
             "request": "launch",
             "program": "${workspaceFolder}/tests/elfio_fuzzer",
             "args": [
-                "crash-da39a3ee5e6b4b0d3255bfef95601890afd80709"
+                "slow-unit-82cabac818b690bc042110f7b073e63462c7553d"
             ],
             "cwd": "${workspaceFolder}/tests",
         }

.vscode/tasks.json

@@ -56,6 +56,30 @@
             "problemMatcher": [
                 "$gcc"
             ]
+        },
+        {
+            "type": "shell",
+            "label": "Fuzzer",
+            "command": "clang",
+            "args": [
+                "-g",
+                "-O0",
+                "-fsanitize=fuzzer",
+                "-I..",
+                "elfio_fuzzer.cpp",
+                "-o",
+                "elfio_fuzzer",
+            ],
+            "options": {
+                "cwd": "${workspaceRoot}/tests"
+            },
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
+            "problemMatcher": [
+                "$gcc"
+            ]
         }
     ],
     "version": "2.0.0"

elfio/elfio.hpp

@@ -473,12 +473,20 @@ class elfio
     }
 
     //------------------------------------------------------------------------------
-    Elf_Half load_sections( std::istream& stream )
+    bool load_sections( std::istream& stream )
     {
+        unsigned char file_class = header->get_class();
         Elf_Half      entry_size = header->get_section_entry_size();
         Elf_Half      num        = header->get_sections_num();
         Elf64_Off     offset     = header->get_sections_offset();
 
+        if ( ( num != 0 && file_class == ELFCLASS64 &&
+               entry_size < sizeof( Elf64_Shdr ) ) ||
+             ( num != 0 && file_class == ELFCLASS32 &&
+               entry_size < sizeof( Elf32_Shdr ) ) ) {
+            return false;
+        }
+
         for ( Elf_Half i = 0; i < num; ++i ) {
             section* sec = create_section();
             sec->load( stream,
@@ -503,7 +511,7 @@ class elfio
             }
         }
 
-        return num;
+        return true;
     }
 
     //------------------------------------------------------------------------------
@@ -526,10 +534,18 @@ class elfio
     //------------------------------------------------------------------------------
     bool load_segments( std::istream& stream )
     {
+        unsigned char file_class = header->get_class();
         Elf_Half      entry_size = header->get_segment_entry_size();
         Elf_Half      num        = header->get_segments_num();
         Elf64_Off     offset     = header->get_segments_offset();
 
+        if ( ( num != 0 && file_class == ELFCLASS64 &&
+               entry_size < sizeof( Elf64_Phdr ) ) ||
+             ( num != 0 && file_class == ELFCLASS32 &&
+               entry_size < sizeof( Elf32_Phdr ) ) ) {
+            return false;
+        }
+
         for ( Elf_Half i = 0; i < num; ++i ) {
             segment*      seg        = nullptr;
             unsigned char file_class = header->get_class();
@@ -546,11 +562,10 @@ class elfio
                 return false;
             }
 
-            seg->load( stream,
+            if ( !seg->load( stream, static_cast<std::streamoff>( offset ) +
-                       static_cast<std::streamoff>( offset ) +
+                                         static_cast<std::streampos>( i ) *
-                           static_cast<std::streampos>( i ) * entry_size );
+                                             entry_size ) ||
-
+                 stream.fail() ) {
-            if ( stream.fail() ) {
                 return false;
             }