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authorManfred Spraul <manfred@colorfullife.com>2008-04-29 01:00:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:14 -0700
commit6013f67fc1a4c7fa5bcab2d39c1eaa3e260c7ac1 (patch)
tree33f61a88048e659359864ec10104e304d8a97a73 /kernel
parent9edff4ab1f8d82675277a04e359d0ed8bf14a7b7 (diff)
ipc: sysvsem: force unshare(CLONE_SYSVSEM) when CLONE_NEWIPC
sys_unshare(CLONE_NEWIPC) doesn't handle the undo lists properly, this can cause a kernel memory corruption. CLONE_NEWIPC must detach from the existing undo lists. Fix, part 2: perform an implicit CLONE_SYSVSEM in CLONE_NEWIPC. CLONE_NEWIPC creates a new IPC namespace, the task cannot access the existing semaphore arrays after the unshare syscall. Thus the task can/must detach from the existing undo list entries, too. This fixes the kernel corruption, because it makes it impossible that undo records from two different namespaces are in sysvsem.undo_list. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Serge E. Hallyn <serue@us.ibm.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')
-rw-r--r--kernel/fork.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 01666979beac..de5c16c6b6ec 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1696,7 +1696,12 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
CLONE_NEWNET))
goto bad_unshare_out;
- if (unshare_flags & CLONE_SYSVSEM)
+ /*
+ * CLONE_NEWIPC must also detach from the undolist: after switching
+ * to a new ipc namespace, the semaphore arrays from the old
+ * namespace are unreachable.
+ */
+ if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
do_sysvsem = 1;
if ((err = unshare_thread(unshare_flags)))
goto bad_unshare_out;