The patch titled
fix sys_unshare()+SEM_UNDO: perform an implicit CLONE_SYSVSEM in CLONE_NEWIPC
has been added to the -mm tree. Its filename is
fix-sys_unsharesem_undo-perform-an-implicit-clone_sysvsem-in-clone_newipc.patch
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------------------------------------------------------
Subject: fix sys_unshare()+SEM_UNDO: perform an implicit CLONE_SYSVSEM in 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.
I'm not sure who's the right maintainer, Andrew, could you merge it?
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: "Serge E. Hallyn" <serue@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx>
Cc: "Pierre Peiffer" <peifferp@xxxxxxxxx>
Cc: Nadia Derbey <Nadia.Derbey@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN kernel/fork.c~fix-sys_unsharesem_undo-perform-an-implicit-clone_sysvsem-in-clone_newipc kernel/fork.c
--- a/kernel/fork.c~fix-sys_unsharesem_undo-perform-an-implicit-clone_sysvsem-in-clone_newipc
+++ a/kernel/fork.c
@@ -1735,9 +1735,13 @@ asmlinkage long sys_unshare(unsigned lon
goto bad_unshare_cleanup_semundo;
if (new_fs || new_mm || new_fd || new_ulist || new_nsproxy) {
- if (unshare_flags & CLONE_SYSVSEM) {
+ if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM)) {
/*
* CLONE_SYSVSEM is equivalent to sys_exit().
+ *
+ * CLONE_NEWIPC must also detach from the undolist: after switching
+ * to a new ipc namespace, the semaphore arrays from the old
+ * namespace are unreachable.
*/
exit_sem(current);
}
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
fix-sys_unsharesem_undo-add-support-for-clone_sysvsem.patch
fix-sys_unsharesem_undo-perform-an-implicit-clone_sysvsem-in-clone_newipc.patch
mm-debug-dump-pageframes-on-bad_page.patch
slab-leaks3-default-y.patch
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