LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Eric Biggers <ebiggers3@gmail.com>,
syzbot <syzbot+71d74a5406d02057d559@syzkaller.appspotmail.com>,
alexander.deucher@amd.com,
Andrey Konovalov <andreyknvl@google.com>,
Anoob Soman <anoob.soman@citrix.com>,
chris@chris-wilson.co.uk, David Miller <davem@davemloft.net>,
"Reshetova, Elena" <elena.reshetova@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
Mike Maloney <maloney@google.com>,
mchehab@kernel.org, netdev <netdev@vger.kernel.org>,
"Rosen, Rami" <rami.rosen@intel.com>,
Sowmini Varadhan <sowmini.varadhan@oracle.com>,
syzkaller-bugs@googlegroups.com,
Willem de Bruijn <willemb@google.com>
Subject: Re: KASAN: use-after-free Read in __dev_queue_xmit
Date: Wed, 9 May 2018 17:05:23 -0400 [thread overview]
Message-ID: <CAF=yD-LwxT6+9U-qCcYEVsPUeL+eVG_aSUZzEM7spwHGb7AQgQ@mail.gmail.com> (raw)
In-Reply-To: <e7be4d14-be04-c40d-82ad-2050876f9ce9@gmail.com>
On Wed, May 9, 2018 at 3:36 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
>
> On 05/09/2018 12:21 PM, Willem de Bruijn wrote:
>
>> Indeed. The skb shared info struct is zeroed by dev_validate_header
>> as a result of dev->hard_header_len exceeding skb->end - skb->data.
>>
>> Not exactly sure yet how this can happen. The hard header length space
>> is accounted for during allocation as reserved memory. But,
>> packet_alloc_skb does call skb_reserve(), moving skb->data
>> effectively beyond this reserved region.
>>
>> It may be incorrect to pass skb->data to dev_validate_header, as that
>> does not point to the start of the ll_header anymore. Still figuring out what
>> the right fix is..
>>
>
> I believe the bug happens if the sock_wmalloc() call at line 1921 has to sleep.
>
> device can change (or at lest dev->hard_header_len can change)
>
> So we need to bailout if reserved/hhlen had changed.
>
> Or revert some patches, since dev_hold() and dev_put() are no longer high cost,
> since it is now using per cpu counter.
Oh nice, another bug :/
That seems quite plausible.
This reproducer does not modify hard_header_len, however.
It sends a long array of zero byte requests with sendmmsg to
eventually exceed so_rcvbuf of the error queue. Hard header
length is 116 throughout.
next prev parent reply other threads:[~2018-05-09 21:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-04 4:58 syzbot
2018-01-04 5:13 ` Eric Dumazet
2018-01-04 6:53 ` Eric Dumazet
2018-05-09 7:37 ` Eric Biggers
2018-05-09 16:11 ` Willem de Bruijn
2018-05-09 16:38 ` Willem de Bruijn
2018-05-09 19:21 ` Willem de Bruijn
2018-05-09 19:36 ` Eric Dumazet
2018-05-09 21:05 ` Willem de Bruijn [this message]
2018-05-10 21:49 ` Willem de Bruijn
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='CAF=yD-LwxT6+9U-qCcYEVsPUeL+eVG_aSUZzEM7spwHGb7AQgQ@mail.gmail.com' \
--to=willemdebruijn.kernel@gmail.com \
--cc=alexander.deucher@amd.com \
--cc=andreyknvl@google.com \
--cc=anoob.soman@citrix.com \
--cc=chris@chris-wilson.co.uk \
--cc=davem@davemloft.net \
--cc=ebiggers3@gmail.com \
--cc=elena.reshetova@intel.com \
--cc=eric.dumazet@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maloney@google.com \
--cc=mchehab@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=rami.rosen@intel.com \
--cc=sowmini.varadhan@oracle.com \
--cc=syzbot+71d74a5406d02057d559@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=willemb@google.com \
--subject='Re: KASAN: use-after-free Read in __dev_queue_xmit' \
/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
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).