As pointed by Al Viro:

https://lkml.org/lkml/2015/4/11/243

There are bugs in ll_getname() because of wrong assumptions of returning
values from strncpy_from_user(). Moreover, what ll_getname want to do is
just to try copy the file name from userland. Since we already have
getname() for the same purpose, it's better to replace ll_getname() with
getname(), so is ll_putname().

Besides, remove unused code for checking whether namelen is 0 or not in
case LL_IOC_REMOVE_ENTRY, because zero-length file name is already
handled by getname() in the same way as ll_getname().

Suggested-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Boqun Feng <boqun.f...@gmail.com>
---
 drivers/staging/lustre/lustre/llite/dir.c          | 60 ++++++----------------
 .../staging/lustre/lustre/llite/llite_internal.h   |  2 +-
 drivers/staging/lustre/lustre/llite/namei.c        |  2 +-
 3 files changed, 18 insertions(+), 46 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/dir.c 
b/drivers/staging/lustre/lustre/llite/dir.c
index a182019..c75fc38 100644
--- a/drivers/staging/lustre/lustre/llite/dir.c
+++ b/drivers/staging/lustre/lustre/llite/dir.c
@@ -1216,30 +1216,6 @@ out:
        return rc;
 }
 
-static char *
-ll_getname(const char __user *filename)
-{
-       int ret = 0, len;
-       char *tmp = __getname();
-
-       if (!tmp)
-               return ERR_PTR(-ENOMEM);
-
-       len = strncpy_from_user(tmp, filename, PATH_MAX);
-       if (len == 0)
-               ret = -ENOENT;
-       else if (len > PATH_MAX)
-               ret = -ENAMETOOLONG;
-
-       if (ret) {
-               __putname(tmp);
-               tmp =  ERR_PTR(ret);
-       }
-       return tmp;
-}
-
-#define ll_putname(filename) __putname(filename)
-
 static long ll_dir_ioctl(struct file *file, unsigned int cmd, unsigned long 
arg)
 {
        struct inode *inode = file_inode(file);
@@ -1441,7 +1417,7 @@ free_lmv:
                return rc;
        }
        case LL_IOC_REMOVE_ENTRY: {
-               char            *filename = NULL;
+               struct filename *name = NULL;
                int              namelen = 0;
                int              rc;
 
@@ -1453,20 +1429,16 @@ free_lmv:
                if (!(exp_connect_flags(sbi->ll_md_exp) & OBD_CONNECT_LVB_TYPE))
                        return -ENOTSUPP;
 
-               filename = ll_getname((const char *)arg);
-               if (IS_ERR(filename))
-                       return PTR_ERR(filename);
+               name = getname((const char *)arg);
+               if (IS_ERR(name))
+                       return PTR_ERR(name);
 
-               namelen = strlen(filename);
-               if (namelen < 1) {
-                       rc = -EINVAL;
-                       goto out_rmdir;
-               }
+               namelen = strlen(name->name);
+
+               rc = ll_rmdir_entry(inode, name->name, namelen);
 
-               rc = ll_rmdir_entry(inode, filename, namelen);
-out_rmdir:
-               if (filename)
-                       ll_putname(filename);
+               if (name)
+                       putname(name);
                return rc;
        }
        case LL_IOC_LOV_SWAP_LAYOUTS:
@@ -1481,16 +1453,16 @@ out_rmdir:
                struct lov_user_md *lump;
                struct lov_mds_md *lmm = NULL;
                struct mdt_body *body;
-               char *filename = NULL;
+               struct filename *name = NULL;
                int lmmsize;
 
                if (cmd == IOC_MDC_GETFILEINFO ||
                    cmd == IOC_MDC_GETFILESTRIPE) {
-                       filename = ll_getname((const char *)arg);
-                       if (IS_ERR(filename))
-                               return PTR_ERR(filename);
+                       name = getname((const char *)arg);
+                       if (IS_ERR(name))
+                               return PTR_ERR(name);
 
-                       rc = ll_lov_getstripe_ea_info(inode, filename, &lmm,
+                       rc = ll_lov_getstripe_ea_info(inode, name->name, &lmm,
                                                      &lmmsize, &request);
                } else {
                        rc = ll_dir_getstripe(inode, &lmm, &lmmsize, &request);
@@ -1556,8 +1528,8 @@ skip_lmm:
 
 out_req:
                ptlrpc_req_finished(request);
-               if (filename)
-                       ll_putname(filename);
+               if (name)
+                       putname(name);
                return rc;
        }
        case IOC_LOV_GETINFO: {
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h 
b/drivers/staging/lustre/lustre/llite/llite_internal.h
index 2af1d72..0950565 100644
--- a/drivers/staging/lustre/lustre/llite/llite_internal.h
+++ b/drivers/staging/lustre/lustre/llite/llite_internal.h
@@ -714,7 +714,7 @@ struct inode *ll_iget(struct super_block *sb, ino_t hash,
 int ll_md_blocking_ast(struct ldlm_lock *, struct ldlm_lock_desc *,
                       void *data, int flag);
 struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de);
-int ll_rmdir_entry(struct inode *dir, char *name, int namelen);
+int ll_rmdir_entry(struct inode *dir, const char *name, int namelen);
 
 /* llite/rw.c */
 int ll_prepare_write(struct file *, struct page *, unsigned from, unsigned to);
diff --git a/drivers/staging/lustre/lustre/llite/namei.c 
b/drivers/staging/lustre/lustre/llite/namei.c
index 890ac19..ec48d8d 100644
--- a/drivers/staging/lustre/lustre/llite/namei.c
+++ b/drivers/staging/lustre/lustre/llite/namei.c
@@ -867,7 +867,7 @@ static inline void ll_get_child_fid(struct dentry *child, 
struct lu_fid *fid)
 /**
  * Remove dir entry
  **/
-int ll_rmdir_entry(struct inode *dir, char *name, int namelen)
+int ll_rmdir_entry(struct inode *dir, const char *name, int namelen)
 {
        struct ptlrpc_request *request = NULL;
        struct md_op_data *op_data;
-- 
2.3.5

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