[lld] r268410 - Check return value of addOptionalSynthetic before calling a member function on it.

[Peter Collingbourne via llvm-commits]

Author: pcc
Date: Tue May  3 13:03:45 2016
New Revision: 268410

URL: http://llvm.org/viewvc/llvm-project?rev=268410&view=rev
Log:
Check return value of addOptionalSynthetic before calling a member function on it.

Found with UBSan.

Modified:
    lld/trunk/ELF/Writer.cpp

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=268410&r1=268409&r2=268410&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Tue May  3 13:03:45 2016
@@ -1207,9 +1207,11 @@ template <class ELFT> void Writer<ELFT>:
 
     // On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between
     // start of function and 'gp' pointer into GOT.
-    ElfSym<ELFT>::MipsGpDisp =
-        addOptionalSynthetic(Symtab, "_gp_disp", Out<ELFT>::Got, MipsGPOffset)
-            ->body();
+    Symbol *Sym =
+        addOptionalSynthetic(Symtab, "_gp_disp", Out<ELFT>::Got, MipsGPOffset);
+    if (Sym)
+      ElfSym<ELFT>::MipsGpDisp = Sym->body();
+
     // The __gnu_local_gp is a magic symbol equal to the current value of 'gp'
     // pointer. This symbol is used in the code generated by .cpload pseudo-op
     // in case of using -mno-shared option.