[llvm] r355073 - [llvm-readobj] - Fix the invalid dumping of the dynamic sections without terminating DT_NULL entry.
George Rimar via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 28 00:15:59 PST 2019
Author: grimar
Date: Thu Feb 28 00:15:59 2019
New Revision: 355073
URL: http://llvm.org/viewvc/llvm-project?rev=355073&view=rev
Log:
[llvm-readobj] - Fix the invalid dumping of the dynamic sections without terminating DT_NULL entry.
This is https://bugs.llvm.org/show_bug.cgi?id=40861,
Previously llvm-readobj would print the DT_NULL sometimes
for the dynamic section that has no terminator entry.
The logic of printDynamicTable was a bit overcomplicated.
I rewrote it slightly to fix the issue and commented.
Differential revision: https://reviews.llvm.org/D58716
Added:
llvm/trunk/test/tools/llvm-readobj/elf-dynamic-table-dtnull.s
Modified:
llvm/trunk/tools/llvm-readobj/ELFDumper.cpp
Added: llvm/trunk/test/tools/llvm-readobj/elf-dynamic-table-dtnull.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-readobj/elf-dynamic-table-dtnull.s?rev=355073&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-readobj/elf-dynamic-table-dtnull.s (added)
+++ llvm/trunk/test/tools/llvm-readobj/elf-dynamic-table-dtnull.s Thu Feb 28 00:15:59 2019
@@ -0,0 +1,78 @@
+# Check we are able to dump the dynamic section without a DT_NULL entry correctly.
+
+# RUN: yaml2obj -docnum=1 %s -o %t.o
+# RUN: llvm-readobj --dynamic-table %t.o | FileCheck %s --check-prefix=NONULL
+# RUN: llvm-readelf --dynamic-table %t.o | FileCheck %s --check-prefix=NONULL
+
+# NONULL: DynamicSection [ (1 entries)
+# NONULL-NEXT: Tag Type Name/Value
+# NONULL-NEXT: 0x0000000000000015 DEBUG 0x0
+# NONULL-NEXT: ]
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .dynamic
+ Type: SHT_DYNAMIC
+ Address: 0x0000000000001010
+ AddressAlign: 0x0000000000000010
+ EntSize: 0x0000000000000010
+ Entries:
+ - Tag: DT_DEBUG
+ Value: 0x0000000000000000
+ProgramHeaders:
+ - Type: PT_LOAD
+ VAddr: 0x1000
+ Sections:
+ - Section: .dynamic
+ - Type: PT_DYNAMIC
+ VAddr: 0x1010
+ Sections:
+ - Section: .dynamic
+
+# Sometimes .dynamic section content length can be greater than the
+# length of its entries. In this case, we should not try to dump anything
+# past the DT_NULL entry, which works as a terminator.
+
+# RUN: yaml2obj -docnum=2 %s -o %t.o
+# RUN: llvm-readobj --dynamic-table %t.o | FileCheck %s --check-prefix=LONG
+# RUN: llvm-readelf --dynamic-table %t.o | FileCheck %s --check-prefix=LONG
+
+# LONG: DynamicSection [ (2 entries)
+# LONG-NEXT: Tag Type Name/Value
+# LONG-NEXT: 0x0000000000000015 DEBUG 0x0
+# LONG-NEXT: 0x0000000000000000 NULL 0x0
+# LONG-NEXT: ]
+
+--- !ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .dynamic
+ Type: SHT_DYNAMIC
+ Address: 0x0000000000001010
+ AddressAlign: 0x0000000000000010
+ EntSize: 0x0000000000000010
+ Entries:
+ - Tag: DT_DEBUG
+ Value: 0x0000000000000000
+ - Tag: DT_NULL
+ Value: 0x0000000000000000
+ - Tag: DT_NULL
+ Value: 0x0000000000000000
+ProgramHeaders:
+ - Type: PT_LOAD
+ VAddr: 0x1000
+ Sections:
+ - Section: .dynamic
+ - Type: PT_DYNAMIC
+ VAddr: 0x1010
+ Sections:
+ - Section: .dynamic
Modified: llvm/trunk/tools/llvm-readobj/ELFDumper.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-readobj/ELFDumper.cpp?rev=355073&r1=355072&r2=355073&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-readobj/ELFDumper.cpp (original)
+++ llvm/trunk/tools/llvm-readobj/ELFDumper.cpp Thu Feb 28 00:15:59 2019
@@ -1914,35 +1914,29 @@ template <> void ELFDumper<ELF32LE>::pri
template<class ELFT>
void ELFDumper<ELFT>::printDynamicTable() {
- auto I = dynamic_table().begin();
- auto E = dynamic_table().end();
+ // A valid .dynamic section contains an array of entries terminated with
+ // a DT_NULL entry. However, sometimes the section content may continue
+ // past the DT_NULL entry, so to dump the section correctly, we first find
+ // the end of the entries by iterating over them.
+ size_t Size = 0;
+ Elf_Dyn_Range DynTableEntries = dynamic_table();
+ for (; Size < DynTableEntries.size();)
+ if (DynTableEntries[Size++].getTag() == DT_NULL)
+ break;
- if (I == E)
- return;
-
- --E;
- while (I != E && E->getTag() == ELF::DT_NULL)
- --E;
- if (E->getTag() != ELF::DT_NULL)
- ++E;
- ++E;
-
- ptrdiff_t Total = std::distance(I, E);
- if (Total == 0)
+ if (!Size)
return;
raw_ostream &OS = W.getOStream();
- W.startLine() << "DynamicSection [ (" << Total << " entries)\n";
+ W.startLine() << "DynamicSection [ (" << Size << " entries)\n";
bool Is64 = ELFT::Is64Bits;
-
W.startLine()
<< " Tag" << (Is64 ? " " : " ") << "Type"
<< " " << "Name/Value\n";
- while (I != E) {
- const Elf_Dyn &Entry = *I;
+ for (size_t I = 0; I < Size; ++I) {
+ const Elf_Dyn &Entry = DynTableEntries[I];
uintX_t Tag = Entry.getTag();
- ++I;
W.startLine() << " " << format_hex(Tag, Is64 ? 18 : 10, opts::Output != opts::GNU) << " "
<< format("%-21s", getTypeString(ObjF->getELFFile()->getHeader()->e_machine, Tag));
printValue(Tag, Entry.getVal());
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