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
| ||
|
Date: Tue, 1 Apr 2008 09:15:41 -0500 From: "Serge E. Hallyn" <serue@...ibm.com> To: Pavel Emelyanov <xemul@...nvz.org> Cc: Manfred Spraul <manfred@...orfullife.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Serge Hallyn <serue@...ibm.com>, Sukadev Bhattiprolu <sukadev@...ibm.com>, "Eric W. Biederman" <ebiederm@...ssion.com> Subject: Re: [RFC, PATCH] fix SEM_UNDO with namespaces Quoting Pavel Emelyanov (xemul@...nvz.org): > Manfred Spraul wrote: > > Pavel Emelyanov wrote: > >> Manfred Spraul wrote: > >> > >>> Hi, > >>> > >>> the attached patch should fix the combination of CLONE_NEWIPC with > >>> shared sysv undo structures (the common case, just > >>> sys_unshare(CLONE_NEWIPC)): > >>> lookup_undo() now locates the undo array based on both semid and the > >>> namespace pointer. > >>> > >> If you start using any IPC object and then call unshare with CLONE_NEWIPC, > >> then it's your problem, but not the kernel. > >> > > The result is a kernel memory corruption, and kernel memory corruptions > > are always the kernel's problem. > > Agree. Must be fixed, but I'm not sure we should try handling this > case by trying to de-op semaphores for former task namespace. I think > that destroying this list or returning -EBUSY for this case is OK. > > > The code assumed that a semaphore id is globally unique. With > > namespaces, this is not true anymore. > > If two semaphore arrays exist with the same id, but different sizes, > > then semops will cause memory corruptions: The undo structure contains > > one element for each semaphore, thus the semop will write behind the end > > of the memory allocation. > > > >> I agree, that we should probably destroy this one when the task calls > >> unshare, but trying to keep this list relevant is useless. > >> > > A very tricky question: Let's assume we have a process with two threads. > > The undo structure is shared, as per opengroup standard. > > Now one thread calls unshare(CLONE_NEWIPC). What should happen? We > > cannot destroy the undo structure, the other thread might be still > > interested in it. > > If we allow sys_unshare() for multithreaded processes with CLONE_NEWIPC > > and without CLONE_SYSVSEM, then we must handle this case. > > Hm... I'd simply disable creating any new namespaces for threads. > I think other namespaces developers agree with me. Serge, Suka, Eric > what do you think? Absolutely. -serge -- 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/
Powered by blists - more mailing lists