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authorSerge E. Hallyn <serue@us.ibm.com>2008-04-29 10:01:00 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 17:06:14 +0200
commit02fdb36ae7f55db7757b623acd27a62d5000d755 (patch)
tree9d96036a7ee174a2828fbb7497a9f365f4f148a1 /kernel/nsproxy.c
parentipc: sysvsem: force unshare(CLONE_SYSVSEM) when CLONE_NEWIPC (diff)
downloadlinux-02fdb36ae7f55db7757b623acd27a62d5000d755.tar.xz
linux-02fdb36ae7f55db7757b623acd27a62d5000d755.zip
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>
Diffstat (limited to 'kernel/nsproxy.c')
-rw-r--r--kernel/nsproxy.c12
1 files changed, 12 insertions, 0 deletions
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);