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-rw-r--r--libc/stdlib/malloc-standard/malloc.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/libc/stdlib/malloc-standard/malloc.h b/libc/stdlib/malloc-standard/malloc.h
index 44120d388..30a696e5a 100644
--- a/libc/stdlib/malloc-standard/malloc.h
+++ b/libc/stdlib/malloc-standard/malloc.h
@@ -839,6 +839,18 @@ 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 CHECK_PTR(P) \
+ if (!aligned_OK(P)) \
+ abort();
/*
morecore_properties is a status word holding dynamically discovered