[CIFS] Don't allow a backslash in a path component

Unless Posix paths have been negotiated, the backslash, "\", is not a valid
character in a path component.

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steve French  <sfrench@us.ibm.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 3830dfeb31cf..82315edc77d7 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -436,6 +436,20 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry, struct name
         cifs_sb = CIFS_SB(parent_dir_inode->i_sb);
         pTcon = cifs_sb->tcon;
 
+        /*
+         * Don't allow the separator character in a path component.
+         * The VFS will not allow "/", but "\" is allowed by posix.
+         */
+        if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
+                int i;
+                for (i = 0; i < direntry->d_name.len; i++)
+                        if (direntry->d_name.name[i] == '\\') {
+                                cFYI(1, ("Invalid file name"));
+                                FreeXid(xid);
+                                return ERR_PTR(-EINVAL);
+                        }
+        }
+
         /* can not grab the rename sem here since it would
         deadlock in the cases (beginning of sys_rename itself)
         in which we already have the sb rename sem */