Re: [PATCH] rds: Error on offset mismatch if not loopback

On 11/14/2013 01:40 AM, Josh Hunt wrote:

On Wed, Nov 13, 2013 at 9:16 AM, Venkat Venkatsubra
[off-list ref] wrote:

quoted

-----Original Message-----
From: Josh Hunt [mailto:joshhunt00@gmail.com]
Sent: Tuesday, November 12, 2013 10:25 PM
To: David Miller
Cc: jjolly@suse.com; LKML; Venkat Venkatsubra; netdev@vger.kernel.org
Subject: Re: [PATCH] rds: Error on offset mismatch if not loopback

On Tue, Nov 12, 2013 at 10:22 PM, Josh Hunt [off-list ref] wrote:

quoted

On Sat, Sep 22, 2012 at 2:25 PM, David Miller [off-list ref] wrote:

quoted

From: John Jolly <redacted>
Date: Fri, 21 Sep 2012 15:32:40 -0600

quoted

Attempting an rds connection from the IP address of an IPoIB
interface to itself causes a kernel panic due to a BUG_ON() being triggered.
Making the test less strict allows rds-ping to work without
crashing the machine.

A local unprivileged user could use this flaw to crash the system.

Signed-off-by: John Jolly <redacted>

Besides the questions being asked of you by Venkat Venkatsubra, this
patch has another issue.

It has been completely corrupted by your email client, it has turned
all TAB characters into spaces, making the patch useless.

Please learn how to send a patch unmolested in the body of your
email.  Test it by emailing the patch to yourself, and verifying that
you can in fact apply the patch you receive in that email.
Then, and only then, should you consider making a new submission of
this patch.

Use Documentation/email-clients.txt for guidance.
--
To unsubscribe from this list: send the line "unsubscribe
linux-kernel" in the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

I think this issue was lost in the shuffle. It appears that redhat,
ubuntu, and oracle are maintaining local patches to resolve this:

https://oss.oracle.com/git/?p=redpatch.git;a=commit;h=c7b6a0a1d8d63685
2be130fa15fa8be10d4704e8
https://bugzilla.redhat.com/show_bug.cgi?id=822754
http://ubuntu.5.x6.nabble.com/CVE-2012-2372-RDS-local-ping-DOS-td49853
88.html

Given that Oracle has applied it I'll make the assumption that
Venkat's question was answered at some point.

David - I can resubmit the patch with the proper signed-off-by and
formatting if you are willing to apply it unless John wants to try
again. I think it's time this got upstream.

--
Josh

Ugh.. hopefully resending with all the html crap removed...

--
Josh

Hi Josh,

No, I still didn't get an answer for how "off" could be non-zero in case of rds-ping to hit BUG_ON(off % RDS_FRAG_SIZE).
Because, rds-ping uses zero byte messages to ping.
If you have a test case that reproduces the kernel panic I can try it out and see how that can happen.
The Oracle's internal code I checked doesn't have that patch applied.

Venkat

No I don't have a test case. I came across this CVE while doing an
audit and noticed it was patched in Ubuntu's kernel and other distros,
but was not in the upstream kernel yet. Quick googling of lkml showed
that there were at least two attempts to get this patch upstream, but
both had issues due to not following the proper submission process:

https://lkml.org/lkml/2012/10/22/433
https://lkml.org/lkml/2012/9/21/505

From my searching it appears the initial bug was found by someone at redhat:
https://bugzilla.redhat.com/show_bug.cgi?id=822754

I've added Li Honggang the reporter of this issue from Redhat to the
mail. Hopefully he can share his testcase.

The test case is very simple:
Steps to Reproduce:
1. yum install -y rds-tools

2. [root@rdma3 ~]# ifconfig ib0 | grep 'inet addr'
          inet addr:172.31.0.3  Bcast:172.31.0.255  Mask:255.255.255.0

3. [root@rdma3 ~]# /usr/bin/rds-ping 172.31.0.3  <<<< kernel panic (You
may need to wait for a few seconds before the kernel panic.)

and possibly requires certain hardware as Jay writes in the first link above:
"...some Infiniband HCAs(QLogic, possibly others) the machine will panic..."

This bug can be reproduced with Mellanox HCAs (mlx4_ib.ko and mthca.ko),
QLogic HCA (ib_qib.ko). I did not test the QLogic HCA running "ib_ipath.ko".

As I know the upstream code of RDS is broken. There are *many* RDS bugs.

Best regards.
Honggang

I was referring to this oracle commit:
https://oss.oracle.com/git/?p=redpatch.git;a=commit;h=c7b6a0a1d8d636852be130fa15fa8be10d4704e8

I have no experience with this code. There were a few comments around
the reset and xmit fns about making sure the caller did certain things
if not they were racy, but I have no idea if that's coming into play
here.