[PATCH] vfs: use kstrdup() and check failing allocation

- use kstrdup() instead of kmalloc() + memcpy()
- return NULL if allocating ->mnt_devname failed
- mnt_devname should be const

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 14 insertions, 12 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index c4fcf48acef8..26380f599534 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -112,9 +112,13 @@ struct vfsmount *alloc_vfsmnt(const char *name)
                 int err;
 
                 err = mnt_alloc_id(mnt);
-                if (err) {
-                        kmem_cache_free(mnt_cache, mnt);
-                        return NULL;
+                if (err)
+                        goto out_free_cache;
+
+                if (name) {
+                        mnt->mnt_devname = kstrdup(name, GFP_KERNEL);
+                        if (!mnt->mnt_devname)
+                                goto out_free_id;
                 }
 
                 atomic_set(&mnt->mnt_count, 1);
@@ -127,16 +131,14 @@ struct vfsmount *alloc_vfsmnt(const char *name)
                 INIT_LIST_HEAD(&mnt->mnt_slave_list);
                 INIT_LIST_HEAD(&mnt->mnt_slave);
                 atomic_set(&mnt->__mnt_writers, 0);
-                if (name) {
-                        int size = strlen(name) + 1;
-                        char *newname = kmalloc(size, GFP_KERNEL);
-                        if (newname) {
-                                memcpy(newname, name, size);
-                                mnt->mnt_devname = newname;
-                        }
-                }
         }
         return mnt;
+
+out_free_id:
+        mnt_free_id(mnt);
+out_free_cache:
+        kmem_cache_free(mnt_cache, mnt);
+        return NULL;
 }
 
 /*
diff --git a/include/linux/mount.h b/include/linux/mount.h
index 4374d1adeb4b..b5efaa2132ab 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -47,7 +47,7 @@ struct vfsmount {
         struct list_head mnt_child;     /* and going through their mnt_child */
         int mnt_flags;
         /* 4 bytes hole on 64bits arches */
-        char *mnt_devname;              /* Name of device e.g. /dev/dsk/hda1 */
+        const char *mnt_devname;        /* Name of device e.g. /dev/dsk/hda1 */
         struct list_head mnt_list;
         struct list_head mnt_expire;    /* link in fs-specific expiry list */
         struct list_head mnt_share;     /* circular list of shared mounts */