public inbox for glibc-cvs@sourceware.org help / color / mirror / Atom feed
From: Szabolcs Nagy <nsz@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc/arm/morello/main] cheri: malloc: Disable pointer protection Date: Fri, 5 Aug 2022 19:35:35 +0000 (GMT) [thread overview] Message-ID: <20220805193535.50B7F3857B9A@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b3d26f52f7084c1f008b3c746c01db4f122f7879 commit b3d26f52f7084c1f008b3c746c01db4f122f7879 Author: Szabolcs Nagy <szabolcs.nagy@arm.com> 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. Diff: --- 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. */ +#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) /*
next reply other threads:[~2022-08-05 19:35 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-05 19:35 Szabolcs Nagy [this message] 2022-10-26 15:18 Szabolcs Nagy 2022-10-27 13:56 Szabolcs Nagy 2022-11-23 14:46 Szabolcs Nagy
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220805193535.50B7F3857B9A@sourceware.org \ --to=nsz@sourceware.org \ --cc=glibc-cvs@sourceware.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).