[PATCH] D35371: [COFF] Bounds check relocations

[Reid Kleckner via Phabricator via llvm-commits]

rnk updated this revision to Diff 106498.
rnk added a comment.

- Mark SectionChunk final
- Hoist loop-invariant getSize call


https://reviews.llvm.org/D35371

Files:
  lld/COFF/Chunks.cpp
  lld/COFF/Chunks.h
  lld/test/COFF/reloc-oob.yaml


Index: lld/test/COFF/reloc-oob.yaml
===================================================================
--- /dev/null
+++ lld/test/COFF/reloc-oob.yaml
@@ -0,0 +1,62 @@
+# Make sure LLD does some light relocation bounds checking.
+
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link %t.obj -entry:main -nodefaultlib -out:%t.exe 2>&1 | FileCheck %s
+
+# CHECK: error: relocation points beyond the end of its parent section
+
+--- !COFF
+header:          
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: [  ]
+sections:        
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     5589E550C745FC00000000A10000000083C4045DC3
+    Relocations:     
+      - VirtualAddress:  24
+        SymbolName:      _g
+        Type:            IMAGE_REL_I386_DIR32
+  - Name:            .data
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+    Alignment:       4
+    SectionData:     2A000000
+symbols:         
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition: 
+      Length:          21
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        662775349
+      Number:          1
+  - Name:            .data
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition: 
+      Length:          4
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        3482275674
+      Number:          2
+  - Name:            _main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            _g
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
Index: lld/COFF/Chunks.h
===================================================================
--- lld/COFF/Chunks.h
+++ lld/COFF/Chunks.h
@@ -112,7 +112,7 @@
 };
 
 // A chunk corresponding a section of an input file.
-class SectionChunk : public Chunk {
+class SectionChunk final : public Chunk {
   // Identical COMDAT Folding feature accesses section internal data.
   friend class ICF;
 
Index: lld/COFF/Chunks.cpp
===================================================================
--- lld/COFF/Chunks.cpp
+++ lld/COFF/Chunks.cpp
@@ -210,7 +210,15 @@
   memcpy(Buf + OutputSectionOff, A.data(), A.size());
 
   // Apply relocations.
+  size_t InputSize = getSize();
   for (const coff_relocation &Rel : Relocs) {
+    // Check for an invalid relocation offset. This check isn't perfect, because
+    // we don't have the relocation size, which is only known after checking the
+    // machine and relocation type. As a result, a relocation may overwrite the
+    // beginning of the following input section.
+    if (Rel.VirtualAddress >= InputSize)
+      fatal("relocation points beyond the end of its parent section");
+
     uint8_t *Off = Buf + OutputSectionOff + Rel.VirtualAddress;
 
     // Get the output section of the symbol for this relocation.  The output


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