From: Jakub Jelinek <jakub@redhat.com>
To: Marek Polacek <polacek@redhat.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>, Jeff Law <law@redhat.com>,
"Joseph S. Myers" <joseph@codesourcery.com>,
rth@redhat.com, gcc-patches List <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] gcc/ubsan.c: Extend 'pretty_name' space to avoid memory overflow
Date: Mon, 17 Nov 2014 08:40:00 -0000 [thread overview]
Message-ID: <20141117073819.GB4079@tucnak.redhat.com> (raw)
In-Reply-To: <20141117071632.GC14744@redhat.com>
On Mon, Nov 17, 2014 at 08:16:32AM +0100, Marek Polacek wrote:
> On Mon, Nov 17, 2014 at 06:40:26AM +0800, Chen Gang wrote:
> > According to the next code, 'pretty_name' may need additional bytes more
> > than 16. For simplify thinking and being extensible in future, extent it
> > to 256 bytes, directly.
>
> I think + 128 bytes should be enough for everyone.
I disagree.
Consider:
typedef char A[1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1][1];
A a;
int foo (int j)
{
a[j][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0][0] = 1;
}
You need 1159 bytes in that case. Easily to construct testcase that needs
arbitrary amount.
I think easiest would be to rewrite the code so that it uses pretty_printer
to construct the string, grep asan.c for asan_pp . Or obstacks, but you don't
have a printer to print integers into it easily.
if (dom && TREE_CODE (TYPE_MAX_VALUE (dom)) == INTEGER_CST)
pos += sprintf (&pretty_name[pos], HOST_WIDE_INT_PRINT_DEC,
tree_to_uhwi (TYPE_MAX_VALUE (dom)) + 1);
else
/* ??? We can't determine the variable name; print VLA unspec. */
pretty_name[pos++] = '*';
looks wrong anyway, as not all integers fit into uhwi.
Guess you could use wide_int to add 1 there and pp_wide_int.
Jakub
next prev parent reply other threads:[~2014-11-17 7:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-17 2:54 Chen Gang
2014-11-17 7:38 ` Marek Polacek
2014-11-17 8:40 ` Jakub Jelinek [this message]
2014-11-17 9:24 ` Marek Polacek
2014-11-17 11:42 ` Chen Gang
2014-11-20 15:34 ` Chen Gang
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=20141117073819.GB4079@tucnak.redhat.com \
--to=jakub@redhat.com \
--cc=gang.chen.5i5j@gmail.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=joseph@codesourcery.com \
--cc=law@redhat.com \
--cc=polacek@redhat.com \
--cc=rth@redhat.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.
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).