fix create_new_namespaces() return value

dup_mnt_ns() and clone_uts_ns() return NULL on failure.  This is wrong,
create_new_namespaces() uses ERR_PTR() to catch an error.  This means that the
subsequent create_new_namespaces() will hit BUG_ON() in copy_mnt_ns() or
copy_utsname().

Modify create_new_namespaces() to also use the errors returned by the
copy_*_ns routines and not to systematically return ENOMEM.

[oleg@tv-sign.ru: better changelog]
Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 28 insertions, 15 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index c811a94e4c88..5585623f6252 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1451,7 +1451,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
 
         new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
         if (!new_ns)
-                return NULL;
+                return ERR_PTR(-ENOMEM);
 
         atomic_set(&new_ns->count, 1);
         INIT_LIST_HEAD(&new_ns->list);
@@ -1465,7 +1465,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
         if (!new_ns->root) {
                 up_write(&namespace_sem);
                 kfree(new_ns);
-                return NULL;
+                return ERR_PTR(-ENOMEM);;
         }
         spin_lock(&vfsmount_lock);
         list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 5aa28e219487..15a6015a849d 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -58,30 +58,41 @@ static struct nsproxy *create_new_namespaces(int flags, struct task_struct *tsk,
                         struct fs_struct *new_fs)
 {
         struct nsproxy *new_nsp;
+        int err;
 
         new_nsp = clone_nsproxy(tsk->nsproxy);
         if (!new_nsp)
                 return ERR_PTR(-ENOMEM);
 
         new_nsp->mnt_ns = copy_mnt_ns(flags, tsk->nsproxy->mnt_ns, new_fs);
-        if (IS_ERR(new_nsp->mnt_ns))
+        if (IS_ERR(new_nsp->mnt_ns)) {
+                err = PTR_ERR(new_nsp->mnt_ns);
                 goto out_ns;
+        }
 
         new_nsp->uts_ns = copy_utsname(flags, tsk->nsproxy->uts_ns);
-        if (IS_ERR(new_nsp->uts_ns))
+        if (IS_ERR(new_nsp->uts_ns)) {
+                err = PTR_ERR(new_nsp->uts_ns);
                 goto out_uts;
+        }
 
         new_nsp->ipc_ns = copy_ipcs(flags, tsk->nsproxy->ipc_ns);
-        if (IS_ERR(new_nsp->ipc_ns))
+        if (IS_ERR(new_nsp->ipc_ns)) {
+                err = PTR_ERR(new_nsp->ipc_ns);
                 goto out_ipc;
+        }
 
         new_nsp->pid_ns = copy_pid_ns(flags, tsk->nsproxy->pid_ns);
-        if (IS_ERR(new_nsp->pid_ns))
+        if (IS_ERR(new_nsp->pid_ns)) {
+                err = PTR_ERR(new_nsp->pid_ns);
                 goto out_pid;
+        }
 
         new_nsp->user_ns = copy_user_ns(flags, tsk->nsproxy->user_ns);
-        if (IS_ERR(new_nsp->user_ns))
+        if (IS_ERR(new_nsp->user_ns)) {
+                err = PTR_ERR(new_nsp->user_ns);
                 goto out_user;
+        }
 
         return new_nsp;
 
@@ -99,7 +110,7 @@ out_uts:
                 put_mnt_ns(new_nsp->mnt_ns);
 out_ns:
         kfree(new_nsp);
-        return ERR_PTR(-ENOMEM);
+        return ERR_PTR(err);
 }
 
 /*
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 89a27e8b17fb..d055d987850c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -34,7 +34,7 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
 
         ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL);
         if (!ns)
-                return NULL;
+                return ERR_PTR(-ENOMEM);
 
         kref_init(&ns->kref);
 
@@ -45,7 +45,7 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
         ns->root_user = alloc_uid(ns, 0);
         if (!ns->root_user) {
                 kfree(ns);
-                return NULL;
+                return ERR_PTR(-ENOMEM);
         }
 
         /* Reset current->user with a new one */
@@ -53,7 +53,7 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
         if (!new_user) {
                 free_uid(ns->root_user);
                 kfree(ns);
-                return NULL;
+                return ERR_PTR(-ENOMEM);
         }
 
         switch_uid(new_user);
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 160c8c5136bd..3ae43936bd88 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -13,6 +13,7 @@
 #include <linux/uts.h>
 #include <linux/utsname.h>
 #include <linux/version.h>
+#include <linux/err.h>
 
 /*
  * Clone a new ns copying an original utsname, setting refcount to 1
@@ -24,10 +25,11 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
         struct uts_namespace *ns;
 
         ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
-        if (ns) {
-                memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
-                kref_init(&ns->kref);
-        }
+        if (!ns)
+                return ERR_PTR(-ENOMEM);
+
+        memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+        kref_init(&ns->kref);
         return ns;
 }