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	9p: validate PDU length
This commit adds length check for the PDU size. The size contained in the header has to match the actual size, except for TCP (trans_fd.c) where actual length is not known ahead and the header's length will be checked only against the validity range. Link: http://lkml.kernel.org/r/20180723154404.2406-1-tomasbortoli@gmail.com Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> Reported-by: syzbot+65c6b72f284a39d416b4@syzkaller.appspotmail.com To: Eric Van Hensbergen <ericvh@gmail.com> To: Ron Minnich <rminnich@sandia.gov> To: Latchesar Ionkov <lucho@ionkov.net> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
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					 4 changed files with 24 additions and 11 deletions
				
			
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			@ -469,20 +469,11 @@ p9_parse_header(struct p9_fcall *pdu, int32_t *size, int8_t *type, int16_t *tag,
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	int err;
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	pdu->offset = 0;
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	if (pdu->size == 0)
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		pdu->size = 7;
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	err = p9pdu_readf(pdu, 0, "dbw", &r_size, &r_type, &r_tag);
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	if (err)
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		goto rewind_and_exit;
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	pdu->size = r_size;
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	pdu->id = r_type;
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	pdu->tag = r_tag;
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	p9_debug(P9_DEBUG_9P, "<<< size=%d type: %d tag: %d\n",
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		 pdu->size, pdu->id, pdu->tag);
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	if (type)
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		*type = r_type;
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	if (tag)
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			@ -490,6 +481,16 @@ p9_parse_header(struct p9_fcall *pdu, int32_t *size, int8_t *type, int16_t *tag,
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	if (size)
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		*size = r_size;
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	if (pdu->size != r_size || r_size < 7) {
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		err = -EINVAL;
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		goto rewind_and_exit;
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	}
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	pdu->id = r_type;
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	pdu->tag = r_tag;
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	p9_debug(P9_DEBUG_9P, "<<< size=%d type: %d tag: %d\n",
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		 pdu->size, pdu->id, pdu->tag);
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rewind_and_exit:
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	if (rewind)
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			@ -516,6 +517,12 @@ static int p9_check_errors(struct p9_client *c, struct p9_req_t *req)
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	int ecode;
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	err = p9_parse_header(req->rc, NULL, &type, NULL, 0);
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	if (req->rc->size >= c->msize) {
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		p9_debug(P9_DEBUG_ERROR,
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			 "requested packet size too big: %d\n",
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			 req->rc->size);
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		return -EIO;
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	}
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	/*
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	 * dump the response from server
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	 * This should be after check errors which poplulate pdu_fcall.
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			@ -325,7 +325,9 @@ static void p9_read_work(struct work_struct *work)
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	if ((!m->req) && (m->rc.offset == m->rc.capacity)) {
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		p9_debug(P9_DEBUG_TRANS, "got new header\n");
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		err = p9_parse_header(&m->rc, NULL, NULL, NULL, 0);
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		/* Header size */
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		m->rc.size = 7;
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		err = p9_parse_header(&m->rc, &m->rc.size, NULL, NULL, 0);
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		if (err) {
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			p9_debug(P9_DEBUG_ERROR,
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				 "error parsing header: %d\n", err);
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			@ -370,6 +372,7 @@ static void p9_read_work(struct work_struct *work)
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	 */
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	if ((m->req) && (m->rc.offset == m->rc.capacity)) {
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		p9_debug(P9_DEBUG_TRANS, "got new packet\n");
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		m->req->rc->size = m->rc.offset;
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		spin_lock(&m->client->lock);
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		if (m->req->status != REQ_STATUS_ERROR)
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			status = REQ_STATUS_RCVD;
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			@ -320,6 +320,7 @@ recv_done(struct ib_cq *cq, struct ib_wc *wc)
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	if (wc->status != IB_WC_SUCCESS)
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		goto err_out;
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	c->rc->size = wc->byte_len;
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	err = p9_parse_header(c->rc, NULL, NULL, &tag, 1);
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	if (err)
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		goto err_out;
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			@ -156,8 +156,10 @@ static void req_done(struct virtqueue *vq)
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			need_wakeup = true;
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		}
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		if (len)
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		if (len) {
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			req->rc->size = len;
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			p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
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		}
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	}
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	spin_unlock_irqrestore(&chan->lock, flags);
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	/* Wakeup if anyone waiting for VirtIO ring space. */
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