Commit 376b43f4 authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: clean up checkSMB 



The variable names in this function are so ambiguous that it's very
difficult to know what it's doing. Rename them to make it a bit more
clear.

Also, remove a redundant length check. cifsd checks to make sure that
the rfclen isn't larger than the maximum frame size when it does the
receive.

Finally, change checkSMB to return a real error code (-EIO) when
it finds an error. That will help simplify some coming changes in the
callers.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent c974befa

fs/cifs/misc.c

+25 −26
Original line number Diff line number Diff line
@@ -420,19 +420,22 @@ check_smb_hdr(struct smb_hdr *smb, __u16 mid) 
}



int

checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length)

checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int total_read)

{

	__u32 len = be32_to_cpu(smb->smb_buf_length);

	__u32 rfclen = be32_to_cpu(smb->smb_buf_length);

	__u32 clc_len;  /* calculated length */

	cFYI(0, "checkSMB Length: 0x%x, smb_buf_length: 0x%x", length, len);

	cFYI(0, "checkSMB Length: 0x%x, smb_buf_length: 0x%x",

		total_read, rfclen);



	if (length < 2 + sizeof(struct smb_hdr)) {

		if ((length >= sizeof(struct smb_hdr) - 1)

	/* is this frame too small to even get to a BCC? */

	if (total_read < 2 + sizeof(struct smb_hdr)) {

		if ((total_read >= sizeof(struct smb_hdr) - 1)

			    && (smb->Status.CifsError != 0)) {

			/* it's an error return */

			smb->WordCount = 0;

			/* some error cases do not return wct and bcc */

			return 0;

		} else if ((length == sizeof(struct smb_hdr) + 1) &&

		} else if ((total_read == sizeof(struct smb_hdr) + 1) &&

				(smb->WordCount == 0)) {

			char *tmp = (char *)smb;

			/* Need to work around a bug in two servers here */
@@ -452,39 +455,35 @@ checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length) 
		} else {

			cERROR(1, "Length less than smb header size");

		}

		return 1;

	}

	if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {

		cERROR(1, "smb length greater than MaxBufSize, mid=%d",

				   smb->Mid);

		return 1;

		return -EIO;

	}



	/* otherwise, there is enough to get to the BCC */

	if (check_smb_hdr(smb, mid))

		return 1;

		return -EIO;

	clc_len = smbCalcSize(smb);



	if (4 + len != length) {

	if (4 + rfclen != total_read) {

		cERROR(1, "Length read does not match RFC1001 length %d",

			   len);

		return 1;

				rfclen);

		return -EIO;

	}



	if (4 + len != clc_len) {

	if (4 + rfclen != clc_len) {

		/* check if bcc wrapped around for large read responses */

		if ((len > 64 * 1024) && (len > clc_len)) {

		if ((rfclen > 64 * 1024) && (rfclen > clc_len)) {

			/* check if lengths match mod 64K */

			if (((4 + len) & 0xFFFF) == (clc_len & 0xFFFF))

			if (((4 + rfclen) & 0xFFFF) == (clc_len & 0xFFFF))

				return 0; /* bcc wrapped */

		}

		cFYI(1, "Calculated size %u vs length %u mismatch for mid=%u",

				clc_len, 4 + len, smb->Mid);

				clc_len, 4 + rfclen, smb->Mid);



		if (4 + len < clc_len) {

		if (4 + rfclen < clc_len) {

			cERROR(1, "RFC1001 size %u smaller than SMB for mid=%u",

					len, smb->Mid);

			return 1;

		} else if (len > clc_len + 512) {

					rfclen, smb->Mid);

			return -EIO;

		} else if (rfclen > clc_len + 512) {

			/*

			 * Some servers (Windows XP in particular) send more

			 * data than the lengths in the SMB packet would
@@ -495,8 +494,8 @@ checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length) 
			 * data to 512 bytes.

			 */

			cERROR(1, "RFC1001 size %u more than 512 bytes larger "

				  "than SMB for mid=%u", len, smb->Mid);

			return 1;

				  "than SMB for mid=%u", rfclen, smb->Mid);

			return -EIO;

		}

	}

	return 0;

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