[CIFS] Fix large (ie over 64K for MaxCIFSBufSize) buffer case for wrapping

bcc on read response and for wrapping sessionsetup maxbufsize field

Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 16 insertions, 11 deletions

diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index 0f3ebad09d3e..988b8cec8568 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -421,9 +421,7 @@ 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));
+        cFYI(0, ("checkSMB Length: 0x%x, smb_buf_length: 0x%x", length, len));
         if (((unsigned int)length < 2 + sizeof (struct smb_hdr)) ||
             (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4)) {
                 if ((unsigned int)length < 2 + sizeof (struct smb_hdr)) {
@@ -435,22 +433,29 @@ checkSMB(struct smb_hdr *smb, __u16 mid, int length)
                         } else {
                                 cERROR(1, ("Length less than smb header size"));
                         }
-
                 }
                 if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4)
-                        cERROR(1,
-                               ("smb_buf_length greater than MaxBufSize"));
-                cERROR(1,
-                       ("bad smb detected. Illegal length. mid=%d",
-                        smb->Mid));
+                        cERROR(1, ("smb length greater than MaxBufSize, mid=%d",
+                                   smb->Mid));
                 return 1;
         }
 
         if (checkSMBhdr(smb, mid))
                 return 1;
         clc_len = smbCalcSize_LE(smb);
-        if ((4 + len != clc_len)
-            || (4 + len != (unsigned int)length)) {
+
+        if(4 + len != (unsigned int)length) {
+                cERROR(1, ("Length read does not match RFC1001 length %d",len));
+                return 1;
+        }
+
+        if (4 + len != clc_len) {
+                /* check if bcc wrapped around for large read responses */
+                if((len > 64 * 1024) && (len > clc_len)) {
+                        /* check if lengths match mod 64K */
+                        if(((4 + len) & 0xFFFF) == (clc_len & 0xFFFF))
+                                return 0; /* bcc wrapped */                     
+                }
                 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));