The patch titled
ipc: sysvsem: force unshare(CLONE_SYSVSEM) when CLONE_NEWIPC
has been added to the -mm tree. Its filename is
ipc-sysvsem-force-unshareclone_sysvsem-when-clone_newipc.patch
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out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ipc: sysvsem: force unshare(CLONE_SYSVSEM) when CLONE_NEWIPC
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxx>
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxxxxxxx>
Cc: Pierre Peiffer <peifferp@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff -puN kernel/fork.c~ipc-sysvsem-force-unshareclone_sysvsem-when-clone_newipc kernel/fork.c
--- a/kernel/fork.c~ipc-sysvsem-force-unshareclone_sysvsem-when-clone_newipc
+++ a/kernel/fork.c
@@ -1707,7 +1707,12 @@ asmlinkage long sys_unshare(unsigned lon
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;
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-sysvsem-implement-sys_unshareclone_sysvsem.patch
ipc-sysvsem-force-unshareclone_sysvsem-when-clone_newipc.patch
ipc-sysvsem-refuse-cloneclone_sysvsemclone_newipc.patch
mm-debug-dump-pageframes-on-bad_page.patch
slab-leaks3-default-y.patch
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