From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Date: Sun, 19 Jun 2011 09:44:35 +0000 (+0530)
Subject: tools/kvm/9p: check the iov count with the read/write count
X-Git-Tag: next-20110824~3^2~190
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9519954ee80e49221f57ae389636e3b010c4f437;p=karo-tx-linux.git

tools/kvm/9p: check the iov count with the read/write count

Make sure we don't read/write more than what is requested
from client.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---

diff --git a/tools/kvm/virtio/9p.c b/tools/kvm/virtio/9p.c
index 24acb585e899..d27017b4cb08 100644
--- a/tools/kvm/virtio/9p.c
+++ b/tools/kvm/virtio/9p.c
@@ -194,6 +194,22 @@ static void set_p9msg_hdr(struct p9_msg *msg, u32 size, u8 cmd, u16 tag)
 	};
 }
 
+static u16 virtio_p9_update_iov_cnt(struct iovec iov[], u32 count, int iov_cnt)
+{
+	int i;
+	u32 total = 0;
+	for (i = 0; (i < iov_cnt) && (total < count); i++) {
+		if (total + iov[i].iov_len > count) {
+			/* we don't need this iov fully */
+			iov[i].iov_len -= ((total + iov[i].iov_len) - count);
+			i++;
+			break;
+		}
+		total += iov[i].iov_len;
+	}
+	return i;
+}
+
 static bool virtio_p9_version(struct p9_dev *p9dev,
 			      struct p9_pdu *pdu, u32 *outlen)
 {
@@ -445,6 +461,9 @@ static bool virtio_p9_read(struct p9_dev *p9dev,
 	} else {
 		pdu->in_iov[0].iov_base += VIRTIO_P9_HDR_LEN + sizeof(u32);
 		pdu->in_iov[0].iov_len -= VIRTIO_P9_HDR_LEN + sizeof(u32);
+		pdu->in_iov_cnt = virtio_p9_update_iov_cnt(pdu->in_iov,
+							    tread->count,
+							    pdu->in_iov_cnt);
 		rread->count = preadv(fid->fd, pdu->in_iov,
 				      pdu->in_iov_cnt, tread->offset);
 		if (rread->count > tread->count)
@@ -549,6 +568,8 @@ static bool virtio_p9_write(struct p9_dev *p9dev,
 
 	pdu->out_iov[0].iov_base += (sizeof(*outmsg) + sizeof(*twrite));
 	pdu->out_iov[0].iov_len -= (sizeof(*outmsg) + sizeof(*twrite));
+	pdu->out_iov_cnt = virtio_p9_update_iov_cnt(pdu->out_iov, twrite->count,
+						    pdu->out_iov_cnt);
 	rwrite->count = pwritev(fid->fd, pdu->out_iov,
 				pdu->out_iov_cnt, twrite->offset);
 	*outlen = VIRTIO_P9_HDR_LEN + sizeof(u32);