[CIFS] Fix byte range locking to Windows when Windows server returns

illegal RFC1001 length (which had caused the lock to block forever
until killed).

1 files changed, 15 insertions, 7 deletions

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 8a0edd695f84..eba1de917f2a 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -420,6 +420,7 @@ int
 checkSMB(struct smb_hdr *smb, __u16 mid, int length)
 {
         __u32 len = smb->smb_buf_length;
+        __u32 clc_len;  /* calculated length */
         cFYI(0,
              ("Entering checkSMB with Length: %x, smb_buf_length: %x ",
               length, len));
@@ -440,20 +441,27 @@ checkSMB(struct smb_hdr *smb, __u16 mid, int length)
                         cERROR(1,
                                ("smb_buf_length greater than MaxBufSize"));
                 cERROR(1,
-                       ("bad smb detected. Illegal length. The mid=%d",
+                       ("bad smb detected. Illegal length. mid=%d",
                         smb->Mid));
                 return 1;
         }
 
         if (checkSMBhdr(smb, mid))
                 return 1;
-
-        if ((4 + len != smbCalcSize_LE(smb))
+        clc_len = smbCalcSize_LE(smb);
+        if ((4 + len != clc_len)
             || (4 + len != (unsigned int)length)) {
-                cERROR(1, ("smbCalcSize %x ", smbCalcSize_LE(smb)));
-                cERROR(1,
-                       ("bad smb size detected. The Mid=%d", smb->Mid));
-                return 1;
+                cERROR(1, ("Calculated size 0x%x vs actual length 0x%x",
+                                clc_len, 4 + len));
+                cERROR(1, ("bad smb size detected for Mid=%d", smb->Mid));
+                /* Windows XP can return a few bytes too much, presumably
+                an illegal pad, at the end of byte range lock responses 
+                so we allow for up to eight byte pad, as long as actual
+                received length is as long or longer than calculated length */
+                if((4+len > clc_len) && (len <= clc_len + 3))
+                        return 0;
+                else
+                        return 1;
         }
         return 0;
 }