cifs: fix CIFS_ENUMERATE_SNAPSHOTS oops

As with 618763958b, an open directory may have a NULL private_data
pointer prior to readdir. CIFS_ENUMERATE_SNAPSHOTS must check for this
before dereference.

Fixes: 834170c859 ("Enable previous version support")
Signed-off-by: David Disseldorp <ddiss@suse.de>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
David Disseldorp 2017-05-03 17:39:08 +02:00 коммит произвёл Steve French
Родитель 0e5c795592
Коммит 6026685de3
1 изменённых файлов: 2 добавлений и 0 удалений

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@ -213,6 +213,8 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
rc = smb_mnt_get_fsinfo(xid, tcon, (void __user *)arg);
break;
case CIFS_ENUMERATE_SNAPSHOTS:
if (pSMBFile == NULL)
break;
if (arg == 0) {
rc = -EINVAL;
goto cifs_ioc_exit;