From: Szabolcs Nagy <nsz@port70.net>
To: "LeMay, Michael" <michael.lemay@intel.com>
Cc: "musl@lists.openwall.com" <musl@lists.openwall.com>
Subject: Re: [RFC PATCH v2 1/4] disable check for buggy brk implementations when SafeStack is enabled
Date: Tue, 1 Nov 2016 23:30:25 +0100 [thread overview]
Message-ID: <20161101223025.GG5749@port70.net> (raw)
In-Reply-To: <390CE752059EB848A71F4F676EBAB76D3AC26355@ORSMSX114.amr.corp.intel.com>
* LeMay, Michael <michael.lemay@intel.com> [2016-10-28 19:56:18 +0000]:
> The check relies on comparing the addresses of stack-allocated objects
> to addresses returned by the brk syscall. SafeStack moves the
> allocations to the unsafe stack, breaking the check. This patch
> disables the check when SafeStack is enabled.
>
> Signed-off-by: Michael LeMay <michael.lemay@...el.com>
> ---
> src/malloc/expand_heap.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/src/malloc/expand_heap.c b/src/malloc/expand_heap.c
> index d8c0be7..af51451 100644
> --- a/src/malloc/expand_heap.c
> +++ b/src/malloc/expand_heap.c
> @@ -13,6 +13,7 @@
>
> static int traverses_stack_p(uintptr_t old, uintptr_t new)
> {
> +#if !defined(__has_feature) || !__has_feature(safe_stack)
preprocessing this fails on any released version of gcc
https://godbolt.org/g/hHWEzI
if __has_feature is not defined it expands to 0 and 0(safe_stack)
is invalid syntax.
e.g. this works:
#ifdef __has_feature
#if __has_feature(safe_stack)
#define HAS_SAFE_STACK 1
#endif
#endif
> const uintptr_t len = 8<<20;
> uintptr_t a, b;
>
> @@ -23,6 +24,7 @@ static int traverses_stack_p(uintptr_t old, uintptr_t new)
> b = (uintptr_t)&b;
> a = b > len ? b-len : 0;
> if (new>a && old<b) return 1;
> +#endif
>
> return 0;
> }
> --
> 2.7.4
prev parent reply other threads:[~2016-11-01 22:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-28 19:56 LeMay, Michael
2016-11-01 22:30 ` Szabolcs Nagy [this message]
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=20161101223025.GG5749@port70.net \
--to=nsz@port70.net \
--cc=michael.lemay@intel.com \
--cc=musl@lists.openwall.com \
/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: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
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 NNTP newsgroup(s).