From 02fdb36ae7f55db7757b623acd27a62d5000d755 Mon Sep 17 00:00:00 2001 From: "Serge E. Hallyn" Date: Tue, 29 Apr 2008 01:01:00 -0700 Subject: [PATCH] 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 Cc: Manfred Spraul Acked-by: "Eric W. Biederman" Cc: Pavel Emelyanov Cc: Michael Kerrisk Cc: Pierre Peiffer Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/nsproxy.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index f5d332cf8c63..adc785146a1c 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -139,6 +139,18 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) goto out; } + /* + * CLONE_NEWIPC must detach from the undolist: after switching + * to a new ipc namespace, the semaphore arrays from the old + * namespace are unreachable. In clone parlance, CLONE_SYSVSEM + * means share undolist with parent, so we must forbid using + * it along with CLONE_NEWIPC. + */ + if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) { + err = -EINVAL; + goto out; + } + new_ns = create_new_namespaces(flags, tsk, tsk->fs); if (IS_ERR(new_ns)) { err = PTR_ERR(new_ns); -- 2.20.1