Handle sections with an unknown section type as errors

Fixes https://github.com/rui314/mold/issues/1215

elf/elf.h

@@ -81,15 +81,19 @@ enum : u32 {
   SHT_GROUP = 17,
   SHT_SYMTAB_SHNDX = 18,
   SHT_RELR = 19,
+  SHT_LOOS = 0x60000000,
   SHT_LLVM_ADDRSIG = 0x6fff4c03,
   SHT_GNU_HASH = 0x6ffffff6,
   SHT_GNU_VERDEF = 0x6ffffffd,
   SHT_GNU_VERNEED = 0x6ffffffe,
   SHT_GNU_VERSYM = 0x6fffffff,
+  SHT_HIOS = 0x6fffffff,
   SHT_X86_64_UNWIND = 0x70000001,
   SHT_ARM_EXIDX = 0x70000001,
   SHT_ARM_ATTRIBUTES = 0x70000003,
   SHT_RISCV_ATTRIBUTES = 0x70000003,
+  SHT_LOUSER = 0x80000000,
+  SHT_HIUSER = 0xffffffff,
 };
 
 enum : u32 {
@@ -100,6 +104,7 @@ enum : u32 {
   SHF_STRINGS = 0x20,
   SHF_INFO_LINK = 0x40,
   SHF_LINK_ORDER = 0x80,
+  SHF_OS_NONCONFORMING = 0x100,
   SHF_GROUP = 0x200,
   SHF_TLS = 0x400,
   SHF_COMPRESSED = 0x800,

elf/input-files.cc

@@ -233,6 +233,32 @@ static void read_riscv_attributes(Context<E> &ctx, ObjectFile<E> &file,
   }
 }
 
+template <typename E>
+static bool is_known_section_type(const ElfShdr<E> &shdr) {
+  u32 ty = shdr.sh_type;
+  u32 flags = shdr.sh_flags;
+
+  if (ty == SHT_PROGBITS ||
+      ty == SHT_NOTE ||
+      ty == SHT_NOBITS ||
+      ty == SHT_INIT_ARRAY ||
+      ty == SHT_FINI_ARRAY ||
+      ty == SHT_PREINIT_ARRAY)
+    return true;
+
+  if (SHT_LOUSER <= ty && ty <= SHT_HIUSER && !(flags & SHF_ALLOC))
+    return true;
+  if (SHT_LOOS <= ty && ty <= SHT_HIOS && !(flags & SHF_OS_NONCONFORMING))
+    return true;
+  if (is_x86<E> && ty == SHT_X86_64_UNWIND)
+    return true;
+  if (is_arm32<E> && (ty == SHT_ARM_EXIDX || ty == SHT_ARM_ATTRIBUTES))
+    return true;
+  if (is_riscv<E> && ty == SHT_RISCV_ATTRIBUTES)
+    return true;
+  return false;
+}
+
 template <typename E>
 void ObjectFile<E>::initialize_sections(Context<E> &ctx) {
   // Read sections
@@ -305,6 +331,10 @@ void ObjectFile<E>::initialize_sections(Context<E> &ctx) {
     case SHT_NULL:
       break;
     default:
+      if (!is_known_section_type(shdr))
+        Fatal(ctx) << *this << ": " << name << ": unsupported section type: 0x"
+                   << std::hex << (u32)shdr.sh_type;
+
       // .note.GNU-stack section controls executable-ness of the stack
       // area in GNU linkers. We ignore that section because silently
       // making the stack area executable is too dangerous. Tell our

test/elf/unkown-section-type.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+. $(dirname $0)/common.inc
+
+# ARM assembler does not seem to accept a hexnum after the atsign
+[ $MACHINE = arm ] && skip
+
+cat <<EOF | $CC -o $t/a.o -c -xassembler -
+.section .my_section,"a",@0x80000000
+EOF
+
+! $CC -B. -o $t/exe $t/a.o >& $t/log1
+grep -q 'unsupported section type: 0x80000000' $t/log1