[llvm] f38f068 - [llvm-readelf] - Do not crash when dumping the dynamic symbol table when its sh_entzize == 0.

[Georgii Rymar via llvm-commits]

Author: Georgii Rymar
Date: 2020-06-22T15:41:34+03:00
New Revision: f38f068b14d8ae131278ae38f55f4e9b77c9d7f8

URL: https://github.com/llvm/llvm-project/commit/f38f068b14d8ae131278ae38f55f4e9b77c9d7f8
DIFF: https://github.com/llvm/llvm-project/commit/f38f068b14d8ae131278ae38f55f4e9b77c9d7f8.diff

LOG: [llvm-readelf] - Do not crash when dumping the dynamic symbol table when its sh_entzize == 0.

We have a division by zero crash currently when
the sh_entzize of the dynamic symbol table is 0.

Differential revision: https://reviews.llvm.org/D82180

Added: 
    

Modified: 
    llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test
    llvm/tools/llvm-readobj/ELFDumper.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test b/llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test
index 0cb338616f94..817d52f41952 100644
--- a/llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test
+++ b/llvm/test/tools/llvm-readobj/ELF/dyn-symbols.test
@@ -490,3 +490,26 @@ ProgramHeaders:
     Sections:
       - Section: .dynstr
       - Section: .dynamic
+
+## Check we report a warning when the entry size of the dynamic symbol table is zero.
+# RUN: yaml2obj %s --docnum=14 -o %t15
+# RUN: llvm-readobj --dyn-symbols %t15 2>&1 | FileCheck %s -DFILE=%t15 --check-prefix=DYNSYM-ZERO-ENTSIZE-LLVM
+# RUN: llvm-readelf --dyn-symbols %t15 2>&1 | \
+# RUN:   FileCheck %s -DFILE=%t15 --check-prefix=DYNSYM-ZERO-ENTSIZE-GNU --implicit-check-not="Symbol table"
+
+# DYNSYM-ZERO-ENTSIZE-LLVM:      DynamicSymbols [
+# DYNSYM-ZERO-ENTSIZE-LLVM-NEXT:  warning: '[[FILE]]': section with index 1 has invalid size (0x10) or entry size (0x0)
+# DYNSYM-ZERO-ENTSIZE-LLVM-NEXT: ]
+
+# DYNSYM-ZERO-ENTSIZE-GNU:  warning: '[[FILE]]': section with index 1 has invalid size (0x10) or entry size (0x0)
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_386
+Sections:
+  - Name:    .dynsym
+    Type:    SHT_DYNSYM
+    EntSize: 0x0

diff  --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index 866cecab66ab..e38ae9d56fb3 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -678,8 +678,7 @@ void ELFDumper<ELFT>::printSymbolsHelper(bool IsDynamic) const {
     StrTable = DynamicStringTable;
     Syms = dynamic_symbols();
     SymtabName = DynSymtabName;
-    if (DynSymRegion)
-      Entries = DynSymRegion->Size / DynSymRegion->EntSize;
+    Entries = Syms.size();
   } else {
     if (!DotSymtabSec)
       return;