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Date: Mon, 07 Apr 2008 11:21:08 +0400 From: Pavel Emelyanov <xemul@...nvz.org> To: Manfred Spraul <manfred@...orfullife.com> CC: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, "Serge E. Hallyn" <serue@...ibm.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, Andrew Morton <akpm@...ux-foundation.org>, Sukadev Bhattiprolu <sukadev@...ibm.com> Subject: Re: [PATCH] fix SEM_UNDO with namespaces, take 2 Manfred Spraul wrote: > Hi, > > below is the second attempt to fix SEM_UNDO + unshare(): > lookup_undo (in ipc/sem.c) is not namespace-aware, thus all entries in > sysvsem.undo_list must be from the same namespace. > The patch enforces that by detaching the current thread from > sysvsem.undo_list in switch_task_namespaces() if the ipc namespace is > changed. > > The patch boots and passes simple sysvsem+unshare tests. > > Signed-Off-By: Manfred Spraul <manfred@...orfullife.com> > > @@ -211,6 +211,18 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) > > might_sleep(); > > + if ((p->nsproxy == NULL && new != NULL) || > + (p->nsproxy != NULL && new == NULL) || > + (p->nsproxy != NULL && new != NULL && p->nsproxy->ipc_ns != new->ipc_ns)) { > + /* switching the IPC namespace is considered equivalent to sys_exit() wrt. > + * to outstanding SEM_UNDO undos: After switching to the new IPC namespace, > + * the semaphore arrays from the old namespace are not accessible anymore. > + * > + * Additionally, an implicit sys_unshare(CLONE_SYSVSEM) is performed. > + */ > + exit_sem(p); > + } > + No, switch_task_namespaces is the wrong place to do this. It is to be done in copy_ipc_ns. If you need a task for which a new namespace is being prepared, then pass one into it. > ns = p->nsproxy; > > rcu_assign_pointer(p->nsproxy, new); -- 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/
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