[lld] 213d184 - [ELF] Improve sh_info=0 and sh_info>=num_sections diagnostic for SHT_REL/SHT_RELA

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2021-11-09T09:54:12-08:00
New Revision: 213d1849a4b9f5579c964086097391907df37a04

URL: https://github.com/llvm/llvm-project/commit/213d1849a4b9f5579c964086097391907df37a04
DIFF: https://github.com/llvm/llvm-project/commit/213d1849a4b9f5579c964086097391907df37a04.diff

LOG: [ELF] Improve sh_info=0 and sh_info>=num_sections diagnostic for SHT_REL/SHT_RELA

PR52408 reported an sh_info=0 instance. I have seen sh_info=0
independently before.

sh_info>=num_sections is probably very rare. Just use one diagnostic for
the two types of errors.

Delete invalid-relocations.test which is covered by invalid/bad-reloc-target.test

Differential Revision: https://reviews.llvm.org/D113466

Added: 
    

Modified: 
    lld/ELF/InputFiles.cpp
    lld/ELF/InputFiles.h
    lld/test/ELF/invalid/bad-reloc-target.test

Removed: 
    lld/test/ELF/invalid-relocations.test


################################################################################
diff  --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index b458b3a2a500..e8a4188ec775 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -837,21 +837,25 @@ template <class ELFT> static uint32_t readAndFeatures(const InputSection &sec) {
 }
 
 template <class ELFT>
-InputSectionBase *ObjFile<ELFT>::getRelocTarget(const Elf_Shdr &sec) {
-  uint32_t idx = sec.sh_info;
-  if (idx >= this->sections.size())
-    fatal(toString(this) + ": invalid relocated section index: " + Twine(idx));
-  InputSectionBase *target = this->sections[idx];
-
-  // Strictly speaking, a relocation section must be included in the
-  // group of the section it relocates. However, LLVM 3.3 and earlier
-  // would fail to do so, so we gracefully handle that case.
-  if (target == &InputSection::discarded)
-    return nullptr;
-
-  if (!target)
-    fatal(toString(this) + ": unsupported relocation reference");
-  return target;
+InputSectionBase *ObjFile<ELFT>::getRelocTarget(uint32_t idx, StringRef name,
+                                                const Elf_Shdr &sec) {
+  uint32_t info = sec.sh_info;
+  if (info < this->sections.size()) {
+    InputSectionBase *target = this->sections[info];
+
+    // Strictly speaking, a relocation section must be included in the
+    // group of the section it relocates. However, LLVM 3.3 and earlier
+    // would fail to do so, so we gracefully handle that case.
+    if (target == &InputSection::discarded)
+      return nullptr;
+
+    if (target != nullptr)
+      return target;
+  }
+
+  error(toString(this) + Twine(": relocation section ") + name + " (index " +
+        Twine(idx) + ") has invalid sh_info (" + Twine(info) + ")");
+  return nullptr;
 }
 
 // Create a regular InputSection class that has the same contents
@@ -939,7 +943,7 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(uint32_t idx,
     // and the group is discarded, even though it's a violation of the
     // spec. We handle that situation gracefully by discarding dangling
     // relocation sections.
-    InputSectionBase *target = getRelocTarget(sec);
+    InputSectionBase *target = getRelocTarget(idx, name, sec);
     if (!target)
       return nullptr;
 

diff  --git a/lld/ELF/InputFiles.h b/lld/ELF/InputFiles.h
index e9566a2dda6a..fb4d46b43f35 100644
--- a/lld/ELF/InputFiles.h
+++ b/lld/ELF/InputFiles.h
@@ -259,7 +259,8 @@ template <class ELFT> class ObjFile : public ELFFileBase {
   void initializeSymbols();
   void initializeJustSymbols();
 
-  InputSectionBase *getRelocTarget(const Elf_Shdr &sec);
+  InputSectionBase *getRelocTarget(uint32_t idx, StringRef name,
+                                   const Elf_Shdr &sec);
   InputSectionBase *createInputSection(uint32_t idx, const Elf_Shdr &sec,
                                        StringRef shstrtab);
 

diff  --git a/lld/test/ELF/invalid-relocations.test b/lld/test/ELF/invalid-relocations.test
deleted file mode 100644
index 53a7981262f1..000000000000
--- a/lld/test/ELF/invalid-relocations.test
+++ /dev/null
@@ -1,23 +0,0 @@
-# RUN: yaml2obj %s -o %t
-# RUN: not ld.lld %t -o /dev/null 2>&1 | FileCheck %s
-
-!ELF
-FileHeader:
-  Class:           ELFCLASS64
-  Data:            ELFDATA2LSB
-  Type:            ET_REL
-  Machine:         EM_X86_64
-Sections:
-  - Type:            SHT_PROGBITS
-  - Name:            .rela.text
-    Type:            SHT_RELA
-    Info:            12 # Invalid index
-    Relocations:
-      - Offset:          0x0000000000000001
-        Symbol:          lulz
-        Type:            R_X86_64_PC32
-Symbols:
-  - Name:            lulz
-    Binding:         STB_GLOBAL
-
-# CHECK: invalid relocated section index

diff  --git a/lld/test/ELF/invalid/bad-reloc-target.test b/lld/test/ELF/invalid/bad-reloc-target.test
index e0948a2c4c76..6177910d881e 100644
--- a/lld/test/ELF/invalid/bad-reloc-target.test
+++ b/lld/test/ELF/invalid/bad-reloc-target.test
@@ -1,6 +1,6 @@
 # RUN: yaml2obj --docnum=1 %s -o %t1.o
 # RUN: not ld.lld %t1.o -o /dev/null 2>&1 | FileCheck %s
-# CHECK: error: {{.*}}.o: unsupported relocation reference
+# CHECK: error: {{.*}}.o: relocation section .rela.text (index 2) has invalid sh_info (0)
 
 --- !ELF
 FileHeader:
@@ -25,7 +25,7 @@ Symbols:
 
 # RUN: yaml2obj --docnum=2 %s -o %t2.o
 # RUN: not ld.lld %t2.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=ERR2
-# ERR2: error: {{.*}}.o: invalid relocated section index: 99
+# ERR2: error: {{.*}}.o: relocation section .rela.text (index 2) has invalid sh_info (99)
 
 --- !ELF
 FileHeader: