ipc: sysvsem: refuse clone(CLONE_SYSVSEM|CLONE_NEWIPC)
CLONE_NEWIPC|CLONE_SYSVSEM interaction isn't handled properly. This can cause a kernel memory corruption. CLONE_NEWIPC must detach from the existing undo lists. Fix, part 3: refuse clone(CLONE_SYSVSEM|CLONE_NEWIPC). With unshare, specifying CLONE_SYSVSEM means unshare the sysvsem. So it seems reasonable that CLONE_NEWIPC without CLONE_SYSVSEM would just imply CLONE_SYSVSEM. However with clone, specifying CLONE_SYSVSEM means *share* the sysvsem. So calling clone(CLONE_SYSVSEM|CLONE_NEWIPC) is explicitly asking for something we can't allow. So return -EINVAL in that case. [akpm@linux-foundation.org: cleanups] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Manfred Spraul <manfred@colorfullife.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Pierre Peiffer <peifferp@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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02fdb36ae7
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@ -139,6 +139,18 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
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goto out;
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}
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/*
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* CLONE_NEWIPC must detach from the undolist: after switching
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* to a new ipc namespace, the semaphore arrays from the old
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* namespace are unreachable. In clone parlance, CLONE_SYSVSEM
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* means share undolist with parent, so we must forbid using
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* it along with CLONE_NEWIPC.
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*/
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if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
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err = -EINVAL;
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goto out;
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}
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new_ns = create_new_namespaces(flags, tsk, tsk->fs);
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if (IS_ERR(new_ns)) {
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err = PTR_ERR(new_ns);
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