Commit 6013f67f authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds

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: default avatarManfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarSerge E. Hallyn <serue@us.ibm.com>
Acked-by: default avatar"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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9edff4ab
......@@ -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;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment