[lld] r304260 - Fix crash when processing relocations in .eh_frame.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Tue May 30 19:23:23 2017
New Revision: 304260

URL: http://llvm.org/viewvc/llvm-project?rev=304260&view=rev
Log:
Fix crash when processing relocations in .eh_frame.

This happens when attempting to link shared libraries using exceptions on
MIPS. It requires -z notext because clang generates R_MIPS_64 relocations
inside .eh_frame.
The crash happened because for EhInputSection the OutSec member is null.

Patch by Alexander Richardson!

Added:
    lld/trunk/test/ELF/mips64-eh-abs-reloc.s
Modified:
    lld/trunk/ELF/SyntheticSections.cpp

Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=304260&r1=304259&r2=304260&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Tue May 30 19:23:23 2017
@@ -1185,7 +1185,7 @@ template <class ELFT> void DynamicSectio
 }
 
 uint64_t DynamicReloc::getOffset() const {
-  return InputSec->OutSec->Addr + InputSec->getOffset(OffsetInSec);
+  return InputSec->getOutputSection()->Addr + InputSec->getOffset(OffsetInSec);
 }
 
 int64_t DynamicReloc::getAddend() const {

Added: lld/trunk/test/ELF/mips64-eh-abs-reloc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/mips64-eh-abs-reloc.s?rev=304260&view=auto
==============================================================================
--- lld/trunk/test/ELF/mips64-eh-abs-reloc.s (added)
+++ lld/trunk/test/ELF/mips64-eh-abs-reloc.s Tue May 30 19:23:23 2017
@@ -0,0 +1,38 @@
+# Having an R_MIPS_64 relocation in eh_frame would previously crash LLD
+# REQUIRES: mips
+# RUN: llvm-mc -filetype=obj -triple=mips64-unknown-freebsd %s -o %t.o
+# RUN: llvm-readobj -r %t.o | FileCheck %s -check-prefix OBJ
+# RUN: ld.lld --eh-frame-hdr -shared -z notext -o %t.so %t.o
+# RUN: llvm-readobj -r %t.so | FileCheck %s -check-prefix PIC-RELOCS
+
+# Linking this as a PIE executable would also previously crash
+# RUN: llvm-mc -filetype=obj -triple=mips64-unknown-freebsd %S/Inputs/archive2.s -o %t-foo.o
+# -pie needs -z notext because of the R_MIPS_64 relocation
+# RUN: ld.lld --eh-frame-hdr -Bdynamic -pie -z notext -o %t-pie-dynamic.exe %t.o %t-foo.o
+# RUN: llvm-readobj -r %t-pie-dynamic.exe | FileCheck %s -check-prefix PIC-RELOCS
+
+
+# OBJ:       Section ({{.*}}) .rela.text {
+# OBJ-NEXT:    0x0 R_MIPS_GPREL16/R_MIPS_SUB/R_MIPS_HI16 foo 0x0
+# OBJ-NEXT:  }
+# OBJ-NEXT:  Section ({{.*}}) .rela.eh_frame {
+# OBJ-NEXT:    0x1C R_MIPS_64/R_MIPS_NONE/R_MIPS_NONE .text 0x0
+# OBJ-NEXT:  }
+
+# PIC-RELOCS: Relocations [
+# PIC-RELOCS-NEXT:  Section (7) .rela.dyn {
+# PIC-RELOCS-NEXT:    {{0x.+}} R_MIPS_REL32/R_MIPS_64/R_MIPS_NONE - 0x10000
+# PIC-RELOCS-NEXT:  }
+# PIC-RELOCS-NEXT:]
+
+
+.globl foo
+
+bar:
+.cfi_startproc
+lui	$11, %hi(%neg(%gp_rel(foo)))
+.cfi_endproc
+
+.globl __start
+__start:
+b bar