This is a note to let you know that I've just added the patch titled nfs4: limit callback decoding to received bytes to the 4.3-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfs4-limit-callback-decoding-to-received-bytes.patch and it can be found in the queue-4.3 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 38b7631fbe42e6e247e9fc9879f961b14a687e3b Mon Sep 17 00:00:00 2001 From: Benjamin Coddington <bcodding@xxxxxxxxxx> Date: Fri, 20 Nov 2015 09:55:30 -0500 Subject: nfs4: limit callback decoding to received bytes From: Benjamin Coddington <bcodding@xxxxxxxxxx> commit 38b7631fbe42e6e247e9fc9879f961b14a687e3b upstream. 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: Benjamin Coddington <bcodding@xxxxxxxxxx> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nfs/callback_xdr.c | 7 +++++-- net/sunrpc/backchannel_rqst.c | 8 ++++++++ net/sunrpc/svc.c | 1 + 3 files changed, 14 insertions(+), 2 deletions(-) --- a/fs/nfs/callback_xdr.c +++ b/fs/nfs/callback_xdr.c @@ -76,7 +76,8 @@ static __be32 *read_buf(struct xdr_strea 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; } @@ -892,6 +893,7 @@ static __be32 nfs4_callback_compound(str 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, @@ -903,7 +905,8 @@ static __be32 nfs4_callback_compound(str 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); --- a/net/sunrpc/backchannel_rqst.c +++ b/net/sunrpc/backchannel_rqst.c @@ -333,12 +333,20 @@ void xprt_complete_bc_request(struct rpc { 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); --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -1363,6 +1363,7 @@ bc_svc_process(struct svc_serv *serv, st 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; Patches currently in stable-queue which might be from bcodding@xxxxxxxxxx are queue-4.3/nfs4-start-callback_ident-at-idr-1.patch queue-4.3/nfs4-limit-callback-decoding-to-received-bytes.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html