[CIFS] Workaround incomplete byte length returned by some
servers on small SMB responses
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 4a4fd2d..f1f8225 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -55,7 +55,7 @@
struct smb_hdr * /* input */ ,
struct smb_hdr * /* out */ ,
int * /* bytes returned */);
-extern int checkSMB(struct smb_hdr *smb, __u16 mid, int length);
+extern int checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length);
extern int is_valid_oplock_break(struct smb_hdr *smb, struct TCP_Server_Info *);
extern int is_size_safe_to_change(struct cifsInodeInfo *);
extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *);
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index ca6e9b1..bbc9cd3 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -418,26 +418,42 @@
}
int
-checkSMB(struct smb_hdr *smb, __u16 mid, int length)
+checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length)
{
__u32 len = smb->smb_buf_length;
__u32 clc_len; /* calculated length */
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)) {
- if (((unsigned int)length >=
- sizeof (struct smb_hdr) - 1)
+
+ if (length < 2 + sizeof (struct smb_hdr)) {
+ if ((length >= sizeof (struct smb_hdr) - 1)
&& (smb->Status.CifsError != 0)) {
- smb->WordCount = 0;
- /* some error cases do not return wct and bcc */
+ smb->WordCount = 0;
+ /* some error cases do not return wct and bcc */
+ return 0;
+ } else if ((length == sizeof(struct smb_hdr) + 1) &&
+ (smb->WordCount == 0)) {
+ char * tmp = (char *)smb;
+ /* Need to work around a bug in two servers here */
+ /* First, check if the part of bcc they sent was zero */
+ if (tmp[sizeof(struct smb_hdr)] == 0) {
+ /* some servers return only half of bcc
+ * on simple responses (wct, bcc both zero)
+ * in particular have seen this on
+ * ulogoffX and FindClose. This leaves
+ * one byte of bcc potentially unitialized
+ */
+ /* zero rest of bcc */
+ tmp[sizeof(struct smb_hdr)+1] = 0;
return 0;
- } else {
- cERROR(1, ("Length less than smb header size"));
}
+ cERROR(1,("rcvd invalid byte count (bcc)"));
+ } else {
+ cERROR(1, ("Length less than smb header size"));
}
- if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4)
- cERROR(1, ("smb length greater than MaxBufSize, mid=%d",
+ return 1;
+ }
+ if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
+ cERROR(1, ("smb length greater than MaxBufSize, mid=%d",
smb->Mid));
return 1;
}
@@ -446,7 +462,7 @@
return 1;
clc_len = smbCalcSize_LE(smb);
- if(4 + len != (unsigned int)length) {
+ if(4 + len != length) {
cERROR(1, ("Length read does not match RFC1001 length %d",len));
return 1;
}
