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Commit a26054d1 authored by Jeff Layton's avatar Jeff Layton Committed by Steve French
Browse files

cifs: sanity check length of data to send before sending 



We had a bug discovered recently where an upper layer function
(cifs_iovec_write) could pass down a smb_rqst with an invalid amount of
data in it. The length of the SMB frame would be correct, but the rqst
struct would cause smb_send_rqst to send nearly 4GB of data.

This should never be the case. Add some sanity checking to the beginning
of smb_send_rqst that ensures that the amount of data we're going to
send agrees with the length in the RFC1002 header. If it doesn't, WARN()
and return -EIO to the upper layers.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Acked-by: default avatarSachin Prabhu <sprabhu@redhat.com>
Reviewed-by: default avatarPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: default avatarSteve French <smfrench@gmail.com>
parent 6b1168e1

fs/cifs/transport.c

+29 −0
Original line number Diff line number Diff line
@@ -270,6 +270,26 @@ cifs_rqst_page_to_kvec(struct smb_rqst *rqst, unsigned int idx, 
		iov->iov_len = rqst->rq_pagesz;

}



static unsigned long

rqst_len(struct smb_rqst *rqst)

{

	unsigned int i;

	struct kvec *iov = rqst->rq_iov;

	unsigned long buflen = 0;



	/* total up iov array first */

	for (i = 0; i < rqst->rq_nvec; i++)

		buflen += iov[i].iov_len;



	/* add in the page array if there is one */

	if (rqst->rq_npages) {

		buflen += rqst->rq_pagesz * (rqst->rq_npages - 1);

		buflen += rqst->rq_tailsz;

	}



	return buflen;

}



static int

smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)

{
@@ -277,6 +297,7 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst) 
	struct kvec *iov = rqst->rq_iov;

	int n_vec = rqst->rq_nvec;

	unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base);

	unsigned long send_length;

	unsigned int i;

	size_t total_len = 0, sent;

	struct socket *ssocket = server->ssocket;
@@ -285,6 +306,14 @@ smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst) 
	if (ssocket == NULL)

		return -ENOTSOCK;



	/* sanity check send length */

	send_length = rqst_len(rqst);

	if (send_length != smb_buf_length + 4) {

		WARN(1, "Send length mismatch(send_length=%lu smb_buf_length=%u)\n",

			send_length, smb_buf_length);

		return -EIO;

	}



	cifs_dbg(FYI, "Sending smb: smb_len=%u\n", smb_buf_length);

	dump_smb(iov[0].iov_base, iov[0].iov_len);