Fix use-of-uninitialized value when RWX memory can't be allocated (PR6701).

SELinux doesn't allow 'execmem', returning MAP_FAILED and 'Permission denied'
for mmap or RWX memory. In this case AllocateRWX was returning a MemoryBlock
with uninitialized fields, which sometimes caused crashes.

This patch initializes MemoryBlock fields to 0, so that the RWX-failure check
works.
It doesn't fix the SELinux 'execmem' issues though (the JIT will not work when
SELinux is in enforcing mode).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99762 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/System/Memory.h b/include/llvm/System/Memory.h
index 69251dd2bfbd6ec7747421fdfa401660797a7a97..01bcab1f0070c2e7f65f3bc0a2880eacf78cb3e6 100644 (file)
--- a/include/llvm/System/Memory.h
+++ b/include/llvm/System/Memory.h
@@ -27,7 +27,7 @@ namespace sys {
   /// @brief Memory block abstraction.
   class MemoryBlock {
   public:
   /// @brief Memory block abstraction.
   class MemoryBlock {
   public:

-    MemoryBlock() { }
+    MemoryBlock() : Address(0), Size(0) { }

     MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
     void *base() const { return Address; }
     size_t size() const { return Size; }
     MemoryBlock(void *addr, size_t size) : Address(addr), Size(size) { }
     void *base() const { return Address; }
     size_t size() const { return Size; }