[PATCH] D64987: [Object/ELF.h] - Improve testing of the fields in ELFFile<ELFT>::sections().

[George Rimar via Phabricator via llvm-commits]

grimar created this revision.
grimar added reviewers: jhenderson, MaskRay.

This eliminates a one error untested and
also introduces a error for one more possible case
which lead to crash previously.

Depends on https://reviews.llvm.org/D64913


https://reviews.llvm.org/D64987

Files:
  include/llvm/Object/ELF.h
  test/Object/invalid.test


Index: test/Object/invalid.test
===================================================================
--- test/Object/invalid.test
+++ test/Object/invalid.test
@@ -552,3 +552,42 @@
 Sections:
   - Name: .foo
     Type: SHT_PROGBITS
+
+## We report a error if the number of sections stored in sh_size
+## is greater than UINT64_MAX / sizeof(Elf_Shdr) = 288230376151711743.
+## Here we check that do not crash on a border value.
+
+# RUN: yaml2obj --docnum=26 %s -o %t26
+# RUN: not llvm-readobj -h %t26 2>&1 | FileCheck -DFILE=%t26 --check-prefix=INVALID-SEC-NUM1 %s
+
+# INVALID-SEC-NUM1: error: '[[FILE]]': invalid number of sections specified in the NULL section's sh_size field (288230376151711743) or e_shoff (64)
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+  SHNum:   0x0
+Sections:
+  - Type: SHT_NULL
+    Size: 288230376151711743
+
+## See above, but now we test the UINT64_MAX / sizeof(Elf_Shdr) value.
+## The error is slightly different in this case.
+
+# RUN: yaml2obj --docnum=27 %s -o %t27
+# RUN: not llvm-readobj -h %t27 2>&1 | FileCheck -DFILE=%t27 --check-prefix=INVALID-SEC-NUM2 %s
+
+# INVALID-SEC-NUM2: '[[FILE]]': invalid number of sections specified in the NULL section's sh_size field (288230376151711744)
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+  SHNum:   0x0
+Sections:
+  - Type: SHT_NULL
+    Size: 288230376151711744
Index: include/llvm/Object/ELF.h
===================================================================
--- include/llvm/Object/ELF.h
+++ include/llvm/Object/ELF.h
@@ -513,11 +513,16 @@
     NumSections = First->sh_size;
 
   if (NumSections > UINT64_MAX / sizeof(Elf_Shdr))
-    // TODO: this error is untested.
-    return createError("section table goes past the end of file");
+    return createError("invalid number of sections specified in the NULL "
+                       "section's sh_size field (" +
+                       Twine(NumSections) + ")");
 
   const uint64_t SectionTableSize = NumSections * sizeof(Elf_Shdr);
-
+  if (SectionTableOffset + SectionTableSize < SectionTableOffset)
+    return createError("invalid number of sections specified in the NULL "
+                       "section's sh_size field (" +
+                       Twine(NumSections) + ") or e_shoff (" +
+                       Twine(SectionTableOffset) + ")");
   // Section table goes past end of file!
   if (SectionTableOffset + SectionTableSize > FileSize)
     return createError("section table goes past the end of file");


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