Re: [RFC PATCH v8 0/5] IPC: checkpoint/restore in userspace enhancements

[Stanislav Kinsbursky]

21.12.2012 00:47, Andrew Morton ÐÐÑÐÑ:
> On Thu, 20 Dec 2012 08:06:32 +0400
> Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx>  wrote:
>
> > 19.12.2012 00:36, Andrew Morton __________:
> > > On Wed, 24 Oct 2012 19:34:51 +0400
> > > Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx>  wrote:
> > >
> > > > This respin of the patch set was significantly reworked. Most part of new API
> > > > was replaced by sysctls (by one per messages, semaphores and shared memory),
> > > > allowing to preset desired id for next new IPC object.
> > > >
> > > > This patch set is aimed to provide additional functionality for all IPC
> > > > objects, which is required for migration of these objects by user-space
> > > > checkpoint/restore utils (CRIU).
> > > >
> > > > The main problem here was impossibility to set up object id. This patch set
> > > > solves the problem by adding new sysctls for preset of desired id for new IPC
> > > > object.
> > > >
> > > > Another problem was to peek messages from queues without deleting them.
> > > > This was achived by introducing of new MSG_COPY flag for sys_msgrcv(). If
> > > > MSG_COPY flag is set, then msgtyp is interpreted as message number.
> > > According to my extensive records, Sasha hit a bug in
> > > ipc-message-queue-copy-feature-introduced.patch and Fengguang found a
> > > bug in
> > > ipc-message-queue-copy-feature-introduced-cleanup-do_msgrcv-aroung-msg_copy-feature.patch
> > >
> > > It's not obvious (to me) that these things have been identified and
> > > fixed.  What's the status, please?
> > Hello, Andrew.
> > Fengguang's issue was solved by "ipc: simplify message copying" I sent you.
> > But I can't find Sasha's issue. As I remember, there was some problem in
> > early
> > version of the patch set. But I believe its fixed now.
> http://lkml.indiana.edu/hypermail/linux/kernel/1210.3/01710.html
>
> Subject: "ipc, msgqueue: NULL ptr deref in msgrcv"

Ah, yes. Thanks.
Hi found it in initial version of code, which was significantly changed 
(or cleaned and simplified) by further patch series.
And I cant find out, how this can happen, because this patch he bisect 
to do not modify the queue itself, while he found the problem in testmsg.


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