Fix out-of-bounds write in case of failing mmap(...) in PosixLockedPageAllocator::AllocateLocked

Author: practicalswift

src/support/allocators/secure.h

@@ -41,7 +41,11 @@ struct secure_allocator : public std::allocator<T> {
 
     T* allocate(std::size_t n, const void* hint = 0)
     {
-        return static_cast<T*>(LockedPoolManager::Instance().alloc(sizeof(T) * n));
+        T* allocation = static_cast<T*>(LockedPoolManager::Instance().alloc(sizeof(T) * n));
+        if (!allocation) {
+            throw std::bad_alloc();
+        }
+        return allocation;
     }
 
     void deallocate(T* p, std::size_t n)

src/support/lockedpool.cpp

@@ -228,6 +228,9 @@ void *PosixLockedPageAllocator::AllocateLocked(size_t len, bool *lockingSuccess)
     void *addr;
     len = align_up(len, page_size);
     addr = mmap(nullptr, len, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+    if (addr == MAP_FAILED) {
+        return nullptr;
+    }
     if (addr) {
         *lockingSuccess = mlock(addr, len) == 0;
     }

src/support/lockedpool.h

@@ -21,7 +21,7 @@ class LockedPageAllocator
     virtual ~LockedPageAllocator() {}
     /** Allocate and lock memory pages.
      * If len is not a multiple of the system page size, it is rounded up.
-     * Returns 0 in case of allocation failure.
+     * Returns nullptr in case of allocation failure.
      *
      * If locking the memory pages could not be accomplished it will still
      * return the memory, however the lockingSuccess flag will be false.