[binutils-gdb/binutils-2_27-branch] [GOLD] PowerPC64 TOC indirect to TOC relative segfault

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d29655b6c3564dc00ff538822c3d383e74697425

commit d29655b6c3564dc00ff538822c3d383e74697425
Author: Alan Modra <amodra@gmail.com>
Date:   Fri Feb 3 19:18:37 2017 +1030

    [GOLD] PowerPC64 TOC indirect to TOC relative segfault
    
    	* powerpc.cc (Powerpc_relobj::make_toc_relative): Don't crash
    	when no .toc section exists.

Diff:
---
 gold/ChangeLog  | 4 ++++
 gold/powerpc.cc | 6 ++++++
 2 files changed, 10 insertions(+)

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 0aeff82..30d3244 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,6 +1,10 @@
 2017-02-22  Alan Modra  <amodra@gmail.com>
 
 	Apply from master
+	2017-02-03  Alan Modra  <amodra@gmail.com>
+	* powerpc.cc (Powerpc_relobj::make_toc_relative): Don't crash
+	when no .toc section exists.
+
 	2017-01-13  H.J. Lu  <hongjiu.lu@intel.com>
 	PR gold/21040
 	* powerpc.cc (Powerpc_relobj<size, big_endian>::make_toc_relative):
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index fec18cd..81f9bff 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -1986,6 +1986,12 @@ Powerpc_relobj<size, big_endian>::make_toc_relative(
   if (size != 64)
     return false;
 
+  // With -mcmodel=medium code it is quite possible to have
+  // toc-relative relocs referring to objects outside the TOC.
+  // Don't try to look at a non-existent TOC.
+  if (this->toc_shndx() == 0)
+    return false;
+
   // Convert VALUE back to an address by adding got_base (see below),
   // then to an offset in the TOC by subtracting the TOC output
   // section address and the TOC output offset.  Since this TOC output