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

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 (file)
index 0000000..4c71584
Binary files /dev/null and b/test/tools/llvm-objdump/Inputs/out-of-section-sym.elf-i386 differ

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 (file)
index 0000000..9a1349c
--- /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 (file)
index 0000000..f70dce6
--- /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 8d934cf94854a28e6d2ecc318828a6bfab6d35a7..d8460fdb247db86f9cd0f1e5cf71cccffae18acf 100644 (file)
--- 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();