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cheri: malloc: Disable pointer protection

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Such arithmetic invalidates capabilities so this security measure does
not work for CHERI.

Note: the architecture makes it hard to corrupt pointers in malloc
metadata, but not impossible: current allocation bounds include the
metadata and capabilities are not revoked after free. These issues can
be fixed by a capability aware malloc.
This commit is contained in:
Szabolcs Nagy 2021-07-07 14:21:40 +01:00
parent 0205012984
commit b3d26f52f7
1 changed files with 4 additions and 0 deletions
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malloc/malloc.c
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@ -341,8 +341,12 @@ Fatal glibc error: malloc assertion failure in %s: %s\n",
It assumes a minimum page size of 4096 bytes (12 bits). Systems with
larger pages provide less entropy, although the pointer mangling
still works. */
#ifdef __CHERI_PURE_CAPABILITY__
#define PROTECT_PTR(pos, ptr) (ptr)
#else
#define PROTECT_PTR(pos, ptr) \
((__typeof (ptr)) ((((size_t) pos) >> 12) ^ ((size_t) ptr)))
#endif
#define REVEAL_PTR(ptr) PROTECT_PTR (&ptr, ptr)
/*