From fb4f2fedd1e4402f1d8a933813c2addb83d07e24 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Fri, 29 Apr 2016 17:46:07 +0000
Subject: [PATCH] Be sure to always increment the Versym pointer.

It was getting out of sync if we had undefined symbols at the start of
the symbol table.

llvm-svn: 268077
---
 lld/ELF/InputFiles.cpp                   |   9 ++++++---
 lld/test/ELF/Inputs/version-undef-sym.so | Bin 0 -> 2312 bytes
 lld/test/ELF/version-undef-sym.s         |  21 +++++++++++++++++++++
 3 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100755 lld/test/ELF/Inputs/version-undef-sym.so
 create mode 100644 lld/test/ELF/version-undef-sym.s

diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index a4b5b718e381..2c7124e6a05c 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -490,16 +490,19 @@ template <class ELFT> void SharedFile<ELFT>::parseRest() {
   uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
   SymbolBodies.reserve(NumSymbols);
   for (const Elf_Sym &Sym : Syms) {
+    unsigned VersymIndex = 0;
+    if (Versym) {
+      VersymIndex = Versym->vs_index;
+      ++Versym;
+    }
+
     StringRef Name = check(Sym.getName(this->StringTable));
     if (Sym.isUndefined()) {
       Undefs.push_back(Name);
       continue;
     }
 
-    unsigned VersymIndex = 0;
     if (Versym) {
-      VersymIndex = Versym->vs_index;
-      ++Versym;
       // Ignore local symbols and non-default versions.
       if (VersymIndex == 0 || (VersymIndex & VERSYM_HIDDEN))
         continue;
diff --git a/lld/test/ELF/Inputs/version-undef-sym.so b/lld/test/ELF/Inputs/version-undef-sym.so
new file mode 100755
index 0000000000000000000000000000000000000000..abb4399cd6c7d48733ac6fef0353b62b97760ee4
GIT binary patch
literal 2312
zcmc&#J#Q015FPtMFdu~@0YZS#r9c89SvcV%1xoCIO^_TSnJ5S-j&p2q3fq$Jh?I(!
zl7B&dN`8hV8cOIvX5Q{T+jlt^&@k4{?7W%To!#3Rf2uX=`CLv&o~#SBle|SL&ak!U
zCMqhjCZ6&OQZT*?Q`4y#*P#^gjSu#~lEhE)7N;Dk4Ky+w%r`Tn^*3<^6D69jXucxn
zbpT7}jC|k&!X9UIoYjH7&gqy(m(}2B7&jDKlAq(W>6QXTUHRDa6DI7FM64NkW#Km!
z&swKE2QSW9=bG_foO}mW4dJeQJ5BPiwO<xxD`2Z&_rV@WD;!GDX@_wrLC}h#Ad16b
ztWdu#aVLsbO3^^}YRv#CD&+-d6XlS&a}YHAHkw~AUQ+#rj)yQPS-+etAHNaUK)7cR
zzvp+Wn(v3{J-0CK7j)ZhYTg0#8kiE!3%Y8B{2Gr3n0|5bzn#uJe>nY+fQ$Pd!qc1K
zxo7wH^j3M^B<@Y_C5bOc)_FX=P2NM&|Ma_o-P8BYI;KCaJ(q!_9)YLp!B-q3O{kx&
zy1J`)Ry{mY+}Dw&#|rpqQ1z;gtaY~L;M<D(I?~isps3x0{f+iLo%mE{W$^U%i|Y3C
zClWks>}*yW!A`yYvbG!SRyP~9z?PV;p4sYRA(khlhjKGTiF(w@sz@n1>cwG8WjwU9
z%UL&!x>9N%_0`47cqpY0{g0)?&M-O{^b<<ZmQtr1ydQ?Wj`0qA2m7;!`1kpB4Mopo
zIq^MHR@~CG7o5(zUsfG8OgrB_Wg%w+(Bm;>JnQ|AVz4oueS?yHLR}2G<){jp+E{x6
z<5@?PSDYv9X}PX;^cdo-H_9~^&m5V*g9YypIWeB^j*@<q>G)S_K##=wAl5JAM+TkR
z8IS)J(2@?u8o;q{_^3+n44<;}{mte+^%Ct1RvWnh^b7un!@}=}|LCm!KfC?k!g+?$
G`~Ly{kDK=Z

literal 0
HcmV?d00001

diff --git a/lld/test/ELF/version-undef-sym.s b/lld/test/ELF/version-undef-sym.s
new file mode 100644
index 000000000000..bdb4795fd1f3
--- /dev/null
+++ b/lld/test/ELF/version-undef-sym.s
@@ -0,0 +1,21 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: llvm-readobj --dyn-symbols %p/Inputs/version-undef-sym.so | FileCheck %s
+
+
+// Show that the input .so has undefined symbols before bar. That is what would
+// get our version parsing out of sync.
+
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Section: Undefined
+// CHECK: Name: bar
+
+// But now we can successfully find bar.
+// RUN: ld.lld %t %p/Inputs/version-undef-sym.so -o %t.exe
+
+        .global _start
+_start:
+        call bar@plt