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From: Szabolcs Nagy <>
Subject: [glibc/arm/morello/main] cheri: malloc: Disable pointer protection
Date: Wed, 26 Oct 2022 15:18:21 +0000 (GMT)	[thread overview]
Message-ID: <> (raw);h=5440678ee1801698f97c52e227aaeff7a84e4516

commit 5440678ee1801698f97c52e227aaeff7a84e4516
Author: Szabolcs Nagy <>
Date:   Wed Jul 7 14:21:40 2021 +0100

    cheri: malloc: Disable pointer protection
    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.

 malloc/malloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index bd3c76ed31..062ca0dc0a 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -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.  */
+#define PROTECT_PTR(pos, ptr) (ptr)
 #define PROTECT_PTR(pos, ptr) \
   ((__typeof (ptr)) ((((size_t) pos) >> 12) ^ ((size_t) ptr)))
 #define REVEAL_PTR(ptr)  PROTECT_PTR (&ptr, ptr)

             reply	other threads:[~2022-10-26 15:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-26 15:18 Szabolcs Nagy [this message]
  -- strict thread matches above, loose matches on Subject: below --
2022-11-23 14:46 Szabolcs Nagy
2022-10-27 13:56 Szabolcs Nagy
2022-08-05 19:35 Szabolcs Nagy

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