cifs: use get/put_unaligned functions to access ByteCount

It's possible that when we access the ByteCount that the alignment
will be off. Most CPUs deal with that transparently, but there's
usually some performance impact. Some CPUs raise an exception on
unaligned accesses.

Fix this by accessing the byte count using the get_unaligned and
put_unaligned inlined functions. While we're at it, fix the types
of some of the variables that end up getting returns from these
functions.

Acked-by: Pavel Shilovsky <[e-mail]>
Signed-off-by: Jeff Layton <[e-mail]>
Signed-off-by: Steve French <[e-mail]>

fs/cifs/cifspdu.h

···
 #define _CIFSPDU_H
 
 #include <net/sock.h>
+#include <asm/unaligned.h>
 #include "smbfsctl.h"
 
 #ifdef CONFIG_CIFS_WEAK_PW_HASH
···
 	__u16 Mid;
 	__u8 WordCount;
 } __attribute__((packed));
-/* given a pointer to an smb_hdr retrieve the value of byte count */
-#define BCC(smb_var) (*(__u16 *)((char *)(smb_var) + sizeof(struct smb_hdr) + (2 * (smb_var)->WordCount)))
-#define BCC_LE(smb_var) (*(__le16 *)((char *)(smb_var) + sizeof(struct smb_hdr) + (2 * (smb_var)->WordCount)))
+
+/* given a pointer to an smb_hdr retrieve a char pointer to the byte count */
+#define BCC(smb_var) ((unsigned char *)(smb_var) + sizeof(struct smb_hdr) + \
+			 (2 * (smb_var)->WordCount))
+
 /* given a pointer to an smb_hdr retrieve the pointer to the byte area */
-#define pByteArea(smb_var) ((unsigned char *)(smb_var) + sizeof(struct smb_hdr) + (2 * (smb_var)->WordCount) + 2)
+#define pByteArea(smb_var) (BCC(smb_var) + 2)
+
+/* get the converted ByteCount for a SMB packet and return it */
+static inline __u16
+get_bcc(struct smb_hdr *hdr)
+{
+	__u16 *bc_ptr = (__u16 *)BCC(hdr);
+
+	return get_unaligned(bc_ptr);
+}
+
+/* get the unconverted ByteCount for a SMB packet and return it */
+static inline __u16
+get_bcc_le(struct smb_hdr *hdr)
+{
+	__le16 *bc_ptr = (__le16 *)BCC(hdr);
+
+	return get_unaligned_le16(bc_ptr);
+}
+
+/* set the ByteCount for a SMB packet in host-byte order */
+static inline void
+put_bcc(__u16 count, struct smb_hdr *hdr)
+{
+	__u16 *bc_ptr = (__u16 *)BCC(hdr);
+
+	put_unaligned(count, bc_ptr);
+}
+
+/* set the ByteCount for a SMB packet in little-endian */
+static inline void
+put_bcc_le(__u16 count, struct smb_hdr *hdr)
+{
+	__le16 *bc_ptr = (__le16 *)BCC(hdr);
+
+	put_unaligned_le16(count, bc_ptr);
+}
 
 /*
  * Computer Name Length (since Netbios name was length 16 with last byte 0x20)

fs/cifs/cifssmb.c

···
 {
 	int rc = -EINVAL;
 	int total_size;
-	char *pBCC;
 
 	/* check for plausible wct, bcc and t2 data and parm sizes */
 	/* check for parm and data offset going beyond end of smb */
···
 			if (total_size < 512) {
 				total_size +=
 					le16_to_cpu(pSMB->t2_rsp.DataCount);
-				/* BCC le converted in SendReceive */
-				pBCC = (pSMB->hdr.WordCount * 2) +
-					sizeof(struct smb_hdr) +
-					(char *)pSMB;
-				if ((total_size <= (*(u16 *)pBCC)) &&
-				   (total_size <
-					CIFSMaxBufSize+MAX_CIFS_HDR_SIZE)) {
+				if (total_size <= get_bcc(&pSMB->hdr) &&
+				    total_size <
+					CIFSMaxBufSize + MAX_CIFS_HDR_SIZE) {
 					return 0;
 				}
 			}
···
 		sizeof(struct smb_t2_rsp) + 16);
 	return rc;
 }
+
 int
 CIFSSMBNegotiate(unsigned int xid, struct cifsSesInfo *ses)
 {
···
 	}
 
 	/* make sure list_len doesn't go past end of SMB */
-	end_of_smb = (char *)pByteArea(&pSMBr->hdr) + BCC(&pSMBr->hdr);
+	end_of_smb = (char *)pByteArea(&pSMBr->hdr) + get_bcc(&pSMBr->hdr);
 	if ((char *)ea_response_data + list_len > end_of_smb) {
 		cFYI(1, "EA list appears to go beyond SMB");
 		rc = -EIO;

fs/cifs/connect.c

···
 	memcpy(data_area_of_target, data_area_of_buf2, total_in_buf2);
 	total_in_buf += total_in_buf2;
 	pSMBt->t2_rsp.DataCount = cpu_to_le16(total_in_buf);
-	byte_count = le16_to_cpu(BCC_LE(pTargetSMB));
+	byte_count = get_bcc_le(pTargetSMB);
 	byte_count += total_in_buf2;
-	BCC_LE(pTargetSMB) = cpu_to_le16(byte_count);
+	put_bcc_le(byte_count, pTargetSMB);
 
 	byte_count = pTargetSMB->smb_buf_length;
 	byte_count += total_in_buf2;
···
 	TCONX_RSP *pSMBr;
 	unsigned char *bcc_ptr;
 	int rc = 0;
-	int length, bytes_left;
-	__u16 count;
+	int length;
+	__u16 bytes_left, count;
 
 	if (ses == NULL)
 		return -EIO;
···
 		tcon->need_reconnect = false;
 		tcon->tid = smb_buffer_response->Tid;
 		bcc_ptr = pByteArea(smb_buffer_response);
-		bytes_left = BCC(smb_buffer_response);
+		bytes_left = get_bcc(smb_buffer_response);
 		length = strnlen(bcc_ptr, bytes_left - 2);
 		if (smb_buffer->Flags2 & SMBFLG2_UNICODE)
 			is_unicode = true;

fs/cifs/netmisc.c

···
 smbCalcSize(struct smb_hdr *ptr)
 {
 	return (sizeof(struct smb_hdr) + (2 * ptr->WordCount) +
-		2 /* size of the bcc field */ + BCC(ptr));
+		2 /* size of the bcc field */ + get_bcc(ptr));
 }
 
 unsigned int
 smbCalcSize_LE(struct smb_hdr *ptr)
 {
 	return (sizeof(struct smb_hdr) + (2 * ptr->WordCount) +
-		2 /* size of the bcc field */ + le16_to_cpu(BCC_LE(ptr)));
+		2 /* size of the bcc field */ + get_bcc_le(ptr));
 }
 
 /* The following are taken from fs/ntfs/util.c */

fs/cifs/sess.c

···
 }
 
 static void
-decode_unicode_ssetup(char **pbcc_area, int bleft, struct cifsSesInfo *ses,
+decode_unicode_ssetup(char **pbcc_area, __u16 bleft, struct cifsSesInfo *ses,
 		      const struct nls_table *nls_cp)
 {
 	int len;
···
 	return;
 }
 
-static int decode_ascii_ssetup(char **pbcc_area, int bleft,
+static int decode_ascii_ssetup(char **pbcc_area, __u16 bleft,
 			       struct cifsSesInfo *ses,
 			       const struct nls_table *nls_cp)
 {
···
 	char *str_area;
 	SESSION_SETUP_ANDX *pSMB;
 	__u32 capabilities;
-	int count;
+	__u16 count;
 	int resp_buf_type;
 	struct kvec iov[3];
 	enum securityEnum type;
-	__u16 action;
-	int bytes_remaining;
+	__u16 action, bytes_remaining;
 	struct key *spnego_key = NULL;
 	__le32 phase = NtLmNegotiate; /* NTLMSSP, if needed, is multistage */
 	u16 blob_len;
···
 	count = iov[1].iov_len + iov[2].iov_len;
 	smb_buf->smb_buf_length += count;
 
-	BCC_LE(smb_buf) = cpu_to_le16(count);
+	put_bcc_le(count, smb_buf);
 
 	rc = SendReceive2(xid, ses, iov, 3 /* num_iovecs */, &resp_buf_type,
 			  CIFS_LOG_ERROR);
···
 	cFYI(1, "UID = %d ", ses->Suid);
 	/* response can have either 3 or 4 word count - Samba sends 3 */
 	/* and lanman response is 3 */
-	bytes_remaining = BCC(smb_buf);
+	bytes_remaining = get_bcc(smb_buf);
 	bcc_ptr = pByteArea(smb_buf);
 
 	if (smb_buf->WordCount == 4) {

fs/cifs/transport.c

···
 	in_buf->smb_buf_length = sizeof(struct smb_hdr) - 4  + 2;
 	in_buf->Command = SMB_COM_NT_CANCEL;
 	in_buf->WordCount = 0;
-	BCC_LE(in_buf) = 0;
+	put_bcc_le(0, in_buf);
 
 	mutex_lock(&server->srv_mutex);
 	rc = cifs_sign_smb(in_buf, server, &mid->sequence_number);
···
 		if (receive_len >= sizeof(struct smb_hdr) - 4
 		    /* do not count RFC1001 header */  +
 		    (2 * midQ->resp_buf->WordCount) + 2 /* bcc */ )
-			BCC(midQ->resp_buf) =
-				le16_to_cpu(BCC_LE(midQ->resp_buf));
+			put_bcc(get_bcc_le(midQ->resp_buf), midQ->resp_buf);
 		if ((flags & CIFS_NO_RESP) == 0)
 			midQ->resp_buf = NULL;  /* mark it so buf will
 						   not be freed by
···
 		if (receive_len >= sizeof(struct smb_hdr) - 4
 		    /* do not count RFC1001 header */  +
 		    (2 * out_buf->WordCount) + 2 /* bcc */ )
-			BCC(out_buf) = le16_to_cpu(BCC_LE(out_buf));
+			put_bcc(get_bcc_le(midQ->resp_buf), midQ->resp_buf);
 	} else {
 		rc = -EIO;
 		cERROR(1, "Bad MID state?");
···
 	if (receive_len >= sizeof(struct smb_hdr) - 4
 	    /* do not count RFC1001 header */  +
 	    (2 * out_buf->WordCount) + 2 /* bcc */ )
-		BCC(out_buf) = le16_to_cpu(BCC_LE(out_buf));
+		put_bcc(get_bcc_le(out_buf), out_buf);
 
 out:
 	delete_mid(midQ);