From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
To: "Carlos O'Donell" <carlos@redhat.com>
Cc: libc-alpha <libc-alpha@sourceware.org>,
"libc-ports@sourceware.org" <libc-ports@sourceware.org>
Subject: Re: [PATCH 2/5] __FD_ELT: Implement correct buffer overflow check
Date: Wed, 01 May 2013 06:28:00 -0000 [thread overview]
Message-ID: <CAHGf_=pDgABHdv5RKd6U870J1t1gM6GhbDpxGoQMjJEsMPHgLQ@mail.gmail.com> (raw)
In-Reply-To: <518080FD.1090402@redhat.com>
>> + ? __fdelt_buffer_warn(__d, __bos0 (s)) \
>
> Space between function and bracket e.g. foo () not foo().
ah, ok.
>
>> + : __fdelt_buffer_chk(__d, __bos0 (s)) \
>> + : __d / __NFDBITS; \
>
> I'm not happy that this isn't very conservative.
>
> If __bos0 fails should we fall back to static FD_SETSIZE checking
> e.g. "__fdelt_buffer_warn (__d, FD_SETSIZE)"?
>
> It seems that that would be better than no checking.
Hmm.. This doesn't cross my mind. All other buffer boundary checks
of _FORTIFY_SOURCE fall back no checking. compiler may fails to
determine a right buffer size in various reasons. at that time, I don't
want to kill innocent applications.
> I know why you want to fall back to no check, because that
> way you don't require any kind of new flag to disable the
> check in the event it triggers when you don't want it to
> (when __bos0 fails).
If you like flag, I'm not putting objection. but if making flag, a lot
of libraries need
to turn on "no check" mode because when a buffer is allocated from applications,
library code can't know a buffer size at least at compile time.
> Does compiling ruby (or similar code) with this header
> result in calls to __fdelt_buffer_warn or __fdelt_buffer_chk?
Unfortunately, No. __builtin_object_size() require compiler know the
buffer size.
In the other words, it doesn't work if an allocate function and
FD_{SET,CLR} functions
doesn't exist in the same place. This is the same limitation with
other string buffer
overflow checks.
next prev parent reply other threads:[~2013-05-01 6:28 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-14 0:47 [PATCH v4 0/5] fix wrong program abort on __FD_ELT KOSAKI Motohiro
2013-04-14 0:47 ` [PATCH 2/5] __FD_ELT: Implement correct buffer overflow check KOSAKI Motohiro
2013-05-01 2:42 ` Carlos O'Donell
2013-05-01 6:28 ` KOSAKI Motohiro [this message]
2013-05-01 14:42 ` Carlos O'Donell
2013-05-01 20:32 ` KOSAKI Motohiro
2013-05-03 3:15 ` Carlos O'Donell
2013-05-01 20:11 ` KOSAKI Motohiro
2013-05-03 3:15 ` Carlos O'Donell
2013-04-14 0:47 ` [PATCH 5/5] __FDS_BITS: Added cast to __fd_mask* to avoid warning KOSAKI Motohiro
2013-05-01 2:44 ` Carlos O'Donell
2013-04-14 0:47 ` [PATCH 3/5] update libc.abilist KOSAKI Motohiro
2013-04-14 0:47 ` [PATCH 1/5] __fdelt_chk: Removed range check KOSAKI Motohiro
2013-05-01 2:25 ` Carlos O'Donell
2013-05-01 6:40 ` KOSAKI Motohiro
2013-05-01 14:45 ` Carlos O'Donell
2013-05-01 22:13 ` KOSAKI Motohiro
2013-05-03 2:52 ` Carlos O'Donell
2013-04-14 0:47 ` [PATCH 4/5] tst-chk1: add fd_set dynamic allocation test KOSAKI Motohiro
2013-05-01 2:44 ` Carlos O'Donell
2013-05-01 6:29 ` KOSAKI Motohiro
2013-05-01 3:08 ` [PATCH v4 0/5] fix wrong program abort on __FD_ELT Carlos O'Donell
2013-05-01 5:31 ` KOSAKI Motohiro
2013-05-01 14:38 ` Carlos O'Donell
2013-05-01 22:21 ` KOSAKI Motohiro
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='CAHGf_=pDgABHdv5RKd6U870J1t1gM6GhbDpxGoQMjJEsMPHgLQ@mail.gmail.com' \
--to=kosaki.motohiro@gmail.com \
--cc=carlos@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=libc-ports@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: link
Be 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).