From 341d0f4b9e8219024093a9cc35dd7b321eaaa0f1 Mon Sep 17 00:00:00 2001
From: Simon Atanasyan <simon@atanasyan.com>
Date: Mon, 24 Feb 2014 22:12:11 +0000
Subject: [PATCH] llvm-objdump: Do not attempt to disassemble symbols outside
 of section boundaries.

It is possible to create an ELF executable where symbol from say .text
section 'points' to the address outside the section boundaries. It does
not have a sense to disassemble something outside the section.

Without this fix llvm-objdump prints finite or infinite (depends on
the executable file architecture) number of 'invalid instruction
encoding' warnings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202083 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Inputs/out-of-section-sym.elf-i386           | Bin 0 -> 4450 bytes
 .../llvm-objdump/Inputs/out-of-section-sym.s     |  15 +++++++++++++++
 test/tools/llvm-objdump/out-of-section-sym.test  |  13 +++++++++++++
 tools/llvm-objdump/llvm-objdump.cpp              |   9 ++++++---
 4 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 test/tools/llvm-objdump/Inputs/out-of-section-sym.elf-i386
 create mode 100644 test/tools/llvm-objdump/Inputs/out-of-section-sym.s
 create mode 100644 test/tools/llvm-objdump/out-of-section-sym.test

diff --git a/test/tools/llvm-objdump/Inputs/out-of-section-sym.elf-i386 b/test/tools/llvm-objdump/Inputs/out-of-section-sym.elf-i386
new file mode 100644
index 0000000000000000000000000000000000000000..4c7158498bafc61a979c0bcb6f5f94e970c2c73c
GIT binary patch
literal 4450
zcmeI0Arits3`NtHGN5P;1_KU-;tHTDxIt$bU@(|=1t<>3wGjNDHcTxJk<6q&Kby3j
zC-=Fl_DPb6MJk!l704}<1yz>luO*kXJ4c^KOwKcNq&BD?PQVE`0Vm)DoPZN>0#3jQ
zH~}Z%1f0O%5_rj`ecWO=LSxhE)v9>D#~=QDfmz-QjFEa*fCs(Bs4q%rW=&{`xz)hi
z4mBP0-<UhV^F7?Bq9xPbLo_OUU~UF#?;EtfCHEP;1>u}|ZcX5qNJaraQ&p>8>NbWZ
MN_{zn7$C~)1MCMGJOBUy

literal 0
HcmV?d00001

diff --git a/test/tools/llvm-objdump/Inputs/out-of-section-sym.s b/test/tools/llvm-objdump/Inputs/out-of-section-sym.s
new file mode 100644
index 00000000000..9a1349c426f
--- /dev/null
+++ b/test/tools/llvm-objdump/Inputs/out-of-section-sym.s
@@ -0,0 +1,15 @@
+// $ cat out-of-section-sym.ld
+// SECTIONS
+// {
+//   . = 0x10;
+//   .text : { _ftext = . ; *(.text) }
+//   . = 0x20;
+//   .data : { _fdata = . ; *(.data) }
+// }
+// as --32 out-of-section-sym.s -o out-of-section-sym.o
+// ld -m elf_i386 -Tout-of-section-sym.ld -o out-of-section-sym.elf-i386 \
+//    out-of-section-sym.o
+
+.text
+_start:
+  ret
diff --git a/test/tools/llvm-objdump/out-of-section-sym.test b/test/tools/llvm-objdump/out-of-section-sym.test
new file mode 100644
index 00000000000..f70dce6a8ed
--- /dev/null
+++ b/test/tools/llvm-objdump/out-of-section-sym.test
@@ -0,0 +1,13 @@
+// Check that llvm-objdump does not attempt to disassemble symbols outside
+// of section boundaries.
+// RUN: llvm-objdump -d -t %p/Inputs/out-of-section-sym.elf-i386 | FileCheck %s
+
+CHECK: Disassembly of section .text:
+CHECK-NEXT: _start:
+CHECK-NEXT:   10:  c3  retl
+CHECK-NEXT: SYMBOL TABLE:
+CHECK-NEXT: 00000000         *UND*  00000000
+CHECK-NEXT: 00000010 l    d  .text  00000000 .text
+CHECK-NEXT: 00000010         .text  00000000 _start
+CHECK-NEXT: 00000020         .text  00000000 _fdata
+CHECK-NEXT: 00000010         .text  00000000 _ftext
diff --git a/tools/llvm-objdump/llvm-objdump.cpp b/tools/llvm-objdump/llvm-objdump.cpp
index 8d934cf9485..d8460fdb247 100644
--- a/tools/llvm-objdump/llvm-objdump.cpp
+++ b/tools/llvm-objdump/llvm-objdump.cpp
@@ -405,6 +405,10 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
     if (error(I->getAddress(SectionAddr)))
       break;
 
+    uint64_t SectSize;
+    if (error(I->getSize(SectSize)))
+      break;
+
     // Make a list of all the symbols in this section.
     std::vector<std::pair<uint64_t, StringRef> > Symbols;
     for (symbol_iterator SI = Obj->symbol_begin(), SE = Obj->symbol_end();
@@ -417,6 +421,8 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
         if (Address == UnknownAddressOrSize)
           continue;
         Address -= SectionAddr;
+        if (Address >= SectSize)
+          continue;
 
         StringRef Name;
         if (error(SI->getName(Name)))
@@ -473,9 +479,6 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
     StringRefMemoryObject memoryObject(Bytes, SectionAddr);
     uint64_t Size;
     uint64_t Index;
-    uint64_t SectSize;
-    if (error(I->getSize(SectSize)))
-      break;
 
     std::vector<RelocationRef>::const_iterator rel_cur = Rels.begin();
     std::vector<RelocationRef>::const_iterator rel_end = Rels.end();