linux-kernel - Re: [RFC][PATCH -mm] IPC: fix error checking in all new xxx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <470DDCAC.4040302@bull.net>
Date:	Thu, 11 Oct 2007 10:19:56 +0200
From:	Nadia Derbey <Nadia.Derbey@...l.net>
To:	Pierre Peiffer <Pierre.Peiffer@...l.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH -mm] IPC: fix error checking in all new xxx_lock()
 functions

Pierre Peiffer wrote:
> In the new implementation of the [sem|shm|msg]_lock[_check]() routines,
> we use the return value of ipc_lock() in container_of() without any check.
> But ipc_lock may return a errcode. The use of this errcode in container_of()
> may alter this errcode, and we don't want this.
> 
> Today, there is no problem because the member used in these container_of()
> is the first member of its container (offset == 0), the errcode isn't changed
> then. But in the general case, we can't count on this assumption and this
> may lead later to a real bug if we don't correct this.
> 
> In fact, the proposed solution is simple and correct. But it has the drawback
> of adding one more check ('if' statement) in the chain: we do a first check in
> ipc_lock(), now in xxx_lock() and then one later in the caller of xxx_lock()
> That's why I send this as RFC, may be another approach could be considered.
> 

This is really what disturbs me this solution: the same check will be 
done several times. But is true that we have to do something.
So why not simply adding a BIG COMMENT before the msg_queue, sem_array 
and shmid_ds stating that the kern_ipc_perm should stay at the beinnign 
of the structure?

Will try to look for another solution.

Regards,
Nadia

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