Commit 38b7631f authored by Benjamin Coddington's avatar Benjamin Coddington Committed by Trond Myklebust
Browse files

nfs4: limit callback decoding to received bytes 



A truncated cb_compound request will cause the client to decode null or
data from a previous callback for nfs4.1 backchannel case, or uninitialized
data for the nfs4.0 case. This is because the path through
svc_process_common() advances the request's iov_base and decrements iov_len
without adjusting the overall xdr_buf's len field.  That causes
xdr_init_decode() to set up the xdr_stream with an incorrect length in
nfs4_callback_compound().

Fixing this for the nfs4.1 backchannel case first requires setting the
correct iov_len and page_len based on the length of received data in the
same manner as the nfs4.0 case.

Then the request's xdr_buf length can be adjusted for both cases based upon
the remaining iov_len and page_len.

Signed-off-by: default avatarBenjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent c68a027c

fs/nfs/callback_xdr.c

+5 −2
Original line number Diff line number Diff line
@@ -78,7 +78,8 @@ static __be32 *read_buf(struct xdr_stream *xdr, int nbytes) 


	p = xdr_inline_decode(xdr, nbytes);

	if (unlikely(p == NULL))

		printk(KERN_WARNING "NFS: NFSv4 callback reply buffer overflowed!\n");

		printk(KERN_WARNING "NFS: NFSv4 callback reply buffer overflowed "

							"or truncated request.\n");

	return p;

}
@@ -889,6 +890,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 
	struct cb_compound_hdr_arg hdr_arg = { 0 };

	struct cb_compound_hdr_res hdr_res = { NULL };

	struct xdr_stream xdr_in, xdr_out;

	struct xdr_buf *rq_arg = &rqstp->rq_arg;

	__be32 *p, status;

	struct cb_process_state cps = {

		.drc_status = 0,
@@ -900,7 +902,8 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r 


	dprintk("%s: start\n", __func__);



	xdr_init_decode(&xdr_in, &rqstp->rq_arg, rqstp->rq_arg.head[0].iov_base);

	rq_arg->len = rq_arg->head[0].iov_len + rq_arg->page_len;

	xdr_init_decode(&xdr_in, rq_arg, rq_arg->head[0].iov_base);



	p = (__be32*)((char *)rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len);

	xdr_init_encode(&xdr_out, &rqstp->rq_res, p);

net/sunrpc/backchannel_rqst.c

+8 −0
Original line number Diff line number Diff line
@@ -353,12 +353,20 @@ void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied) 
{

	struct rpc_xprt *xprt = req->rq_xprt;

	struct svc_serv *bc_serv = xprt->bc_serv;

	struct xdr_buf *rq_rcv_buf = &req->rq_rcv_buf;



	spin_lock(&xprt->bc_pa_lock);

	list_del(&req->rq_bc_pa_list);

	xprt_dec_alloc_count(xprt, 1);

	spin_unlock(&xprt->bc_pa_lock);



	if (copied <= rq_rcv_buf->head[0].iov_len) {

		rq_rcv_buf->head[0].iov_len = copied;

		rq_rcv_buf->page_len = 0;

	} else {

		rq_rcv_buf->page_len = copied - rq_rcv_buf->head[0].iov_len;

	}



	req->rq_private_buf.len = copied;

	set_bit(RPC_BC_PA_IN_USE, &req->rq_bc_pa_state);

net/sunrpc/svc.c

+1 −0
Original line number Diff line number Diff line
@@ -1363,6 +1363,7 @@ bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req, 
	memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);

	memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg));

	memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res));

	rqstp->rq_arg.len = req->rq_private_buf.len;



	/* reset result send buffer "put" position */

	resv->iov_len = 0;

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