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Subject[PATCH -next] fork.c: Move check of clone NEWIPC and SYSVSEM to copy_process
Date
Currently this check for CLONE_NEWIPC with CLONE_SYSVSEM is done inside
copy_namespaces, resulting in a handful of error paths being executed if
these flags were used together. So, move this check to the beginning of
copy_process, exiting earlier if the condition is true.

This move is safe because copy_namespaces is called just from
copy_process function.

Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
---
kernel/fork.c | 11 +++++++++++
kernel/nsproxy.c | 11 -----------
2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 2113e252cb9d..691f9ba135fc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1600,6 +1600,17 @@ static __latent_entropy struct task_struct *copy_process(
return ERR_PTR(-EINVAL);

/*
+ * 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 ((clone_flags & (CLONE_NEWIPC | CLONE_SYSVSEM)) ==
+ (CLONE_NEWIPC | CLONE_SYSVSEM))
+ return ERR_PTR(-EINVAL);
+
+ /*
* Thread groups must share signals as well, and detached threads
* can only be started up within the thread group.
*/
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f6c5d330059a..30882727dff5 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -151,17 +151,6 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return -EPERM;

- /*
- * 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 | CLONE_SYSVSEM)) ==
- (CLONE_NEWIPC | CLONE_SYSVSEM))
- return -EINVAL;
-
new_ns = create_new_namespaces(flags, tsk, user_ns, tsk->fs);
if (IS_ERR(new_ns))
return PTR_ERR(new_ns);
--
2.13.6
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