From: Florian Westphal <fw@strlen.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: syzbot <syzbot+e86f7c428c8c50db65b4@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
coreteam@netfilter.org, David Miller <davem@davemloft.net>,
Florian Westphal <fw@strlen.de>, Jakub Jelinek <jakub@redhat.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Jozsef Kadlecsik <kadlec@netfilter.org>,
Jakub Kicinski <kuba@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Netdev <netdev@vger.kernel.org>,
NetFilter <netfilter-devel@vger.kernel.org>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Peter Zijlstra <peterz@infradead.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Tejun Heo <tj@kernel.org>
Subject: Re: kernel BUG at lib/string.c:LINE! (6)
Date: Tue, 22 Dec 2020 23:07:19 +0100 [thread overview]
Message-ID: <20201222220719.GB9639@breakpoint.cc> (raw)
In-Reply-To: <CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com>
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Dec 22, 2020 at 6:44 AM syzbot
> <syzbot+e86f7c428c8c50db65b4@syzkaller.appspotmail.com> wrote:
> >
> > The issue was bisected to:
> >
> > commit 2f78788b55ba ("ilog2: improve ilog2 for constant arguments")
>
> That looks unlikely, although possibly some constant folding
> improvement might make the fortify code notice something with it.
>
> > detected buffer overflow in strlen
> > ------------[ cut here ]------------
> > kernel BUG at lib/string.c:1149!
> > Call Trace:
> > strlen include/linux/string.h:325 [inline]
> > strlcpy include/linux/string.h:348 [inline]
> > xt_rateest_tg_checkentry+0x2a5/0x6b0 net/netfilter/xt_RATEEST.c:143
>
> Honestly, this just looks like the traditional bug in "strlcpy()".
Yes, thats exactly what this is, no idea why the bisection points
at ilog2 changes.
> That BSD function is complete garbage, exactly because it doesn't
> limit the source length. People tend to _think_ it does ("what's that
> size_t argument for?") but strlcpy() only limits the *destination*
> size, and the source is always read fully.
Right, I'll send a patch shortly.
next prev parent reply other threads:[~2020-12-22 22:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-22 14:44 kernel BUG at lib/string.c:LINE! (6) syzbot
2020-12-22 22:01 ` Linus Torvalds
2020-12-22 22:07 ` Florian Westphal [this message]
2020-12-23 11:25 ` Dmitry Vyukov
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=20201222220719.GB9639@breakpoint.cc \
--to=fw@strlen.de \
--cc=akpm@linux-foundation.org \
--cc=coreteam@netfilter.org \
--cc=davem@davemloft.net \
--cc=jakub@redhat.com \
--cc=jiangshanlai@gmail.com \
--cc=kadlec@netfilter.org \
--cc=kuba@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=netfilter-devel@vger.kernel.org \
--cc=pablo@netfilter.org \
--cc=peterz@infradead.org \
--cc=syzbot+e86f7c428c8c50db65b4@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=tj@kernel.org \
--cc=torvalds@linux-foundation.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 NNTP newsgroup(s).