Messages in this thread Patch in this message | | | From | Manfred Spraul <> | Date | Sun, 13 Apr 2008 10:09:30 +0200 | Subject | [PATCH 2/2] fix sys_unshare()+SEM_UNDO: perform an implicit CLONE_SYSVSEM in 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.
I'm not sure who's the right maintainer, Andrew, could you merge it?
Signed-off-by: Manfred Spraul <manfred@colorfullife.com> --- kernel/fork.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c index 7f242b0..6f956a7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1735,9 +1735,13 @@ asmlinkage long sys_unshare(unsigned long unshare_flags) 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); } -- 1.5.4.1
| |