[ 08/53] namespaces, pid_ns: fix leakage on fork() failure

3.2.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Galbraith <redacted>

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 <redacted>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: "Eric W. Biederman" <redacted>
Cc: Pavel Emelyanov <redacted>
Cc: Cyrill Gorcunov <redacted>
Cc: Louis Rilling <redacted>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <redacted>
---
 kernel/fork.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index b9372a0..687a15d 100644
--- 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>

@@ -1464,6 +1465,8 @@ 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)

-- 
1.7.10