1 files changed, 16 insertions, 0 deletions
diff --git a/libc/stdlib/malloc-standard/malloc.h b/libc/stdlib/malloc-standard/malloc.h
index 44120d388..f196a560f 100644
--- a/libc/stdlib/malloc-standard/malloc.h
+++ b/libc/stdlib/malloc-standard/malloc.h
@@ -23,6 +23,7 @@
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <bits/uClibc_mutex.h>
+#include <bits/uClibc_page.h>
 
 
 
@@ -839,6 +840,21 @@ typedef struct malloc_chunk* mfastbinptr;
 #define get_max_fast(M) \
   ((M)->max_fast & ~(FASTCHUNKS_BIT | ANYCHUNKS_BIT))
 
+/*
+  Safe-Linking:
+  Use randomness from ASLR (mmap_base) to protect single-linked lists
+  of fastbins. Together with allocation alignment checks, this mechanism
+  reduces the risk of pointer hijacking, as was done with Safe-Unlinking
+  in the double-linked lists of smallbins.
+*/
+#define PROTECT_PTR(pos, ptr)     ((mchunkptr)((((size_t)pos) >> PAGE_SHIFT) ^ ((size_t)ptr)))
+#define REVEAL_PTR(pos, ptr)      PROTECT_PTR(pos, ptr)
+#define PTR_FOR_ALIGNMENT_CHECK(P) \
+    (MALLOC_ALIGNMENT == 2*(sizeof(size_t)) ? (P) : chunk2mem(P))
+
+#define CHECK_PTR(P)                            \
+  if (!aligned_OK(PTR_FOR_ALIGNMENT_CHECK(P)))  \
+      abort();
 
 /*
   morecore_properties is a status word holding dynamically discovered