Messages in this thread Patch in this message | | | Date | Wed, 16 Apr 2008 11:44:10 -0500 | From | "Serge E. Hallyn" <> | Subject | [PATCH 3/3] ipc: sysvsem: refuse clone(CLONE_SYSVSEM|CLONE_NEWIPC) |
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CLONE_NEWIPC|CLONE_SYSVSEM interaction isn't handled properly. This can cause a kernel memory corruption. CLONE_NEWIPC must detach from the existing undo lists. Fix, part 3: refuse clone(CLONE_SYSVSEM|CLONE_NEWIPC).
With unshare, specifying CLONE_SYSVSEM means unshare the sysvsem. So it seems reasonable that CLONE_NEWIPC without CLONE_SYSVSEM would just imply CLONE_SYSVSEM.
However with clone, specifying CLONE_SYSVSEM means *share* the sysvsem. So calling clone(CLONE_SYSVSEM|CLONE_NEWIPC) is explicitly asking for something we can't allow. So return -EINVAL in that case.
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> --- kernel/nsproxy.c | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index f5d332c..468ade3 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -139,6 +139,18 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) goto out; } + /* + * CLONE_NEWIPC must detach from the undolist: after switching + * to a new ipc namespace, the semaphore arrays from the old + * namespace are unreachable. In clone parlance, CLONE_SYSVSEM + * means share undolist with parent, so we must forbid using + * it along with CLONE_NEWIPC. + */ + if ((flags&CLONE_NEWIPC) && (flags&CLONE_SYSVSEM)) { + err = -EINVAL; + goto out; + } + new_ns = create_new_namespaces(flags, tsk, tsk->fs); if (IS_ERR(new_ns)) { err = PTR_ERR(new_ns); -- 1.5.1.1.GIT
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