namespaces, pid_ns: fix leakage on fork() failure

commit 5e2bf0142231194d36fdc9596b36a261ed2b9fe7 upstream.

Fork() failure post namespace creation for a child cloned with
CLONE_NEWPID leaks pid_namespace/mnt_cache due to proc being mounted
during creation, but not unmounted during cleanup.  Call
pid_ns_release_proc() during cleanup.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/fork.c b/kernel/fork.c
index 0acf42c0af50ca19b47828aa6158105a707d08e8..26f1ab0b1c95fea8409cc9f3d67ac94315cf40ac 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -47,6 +47,7 @@
 #include <linux/audit.h>
 #include <linux/memcontrol.h>
 #include <linux/ftrace.h>
+#include <linux/proc_fs.h>
 #include <linux/profile.h>
 #include <linux/rmap.h>
 #include <linux/ksm.h>
@@ -1387,6 +1388,8 @@ bad_fork_cleanup_io:
        if (p->io_context)
                exit_io_context(p);
 bad_fork_cleanup_namespaces:
+       if (unlikely(clone_flags & CLONE_NEWPID))
+               pid_ns_release_proc(p->nsproxy->pid_ns);
        exit_task_namespaces(p);
 bad_fork_cleanup_mm:
        if (p->mm)