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xprtrdma: Replace use of xdr_stream_pos in rpcrdma_marshal_req 

This is a latent bug. xdr_stream_pos works by subtracting
xdr_stream::nwords from xdr_buf::len. But xdr_stream::nwords is not
initialized by xdr_init_encode().

It works today only because all fields in rpcrdma_req::rl_stream
are initialized to zero by rpcrdma_req_create, making the
subtraction in xdr_stream_pos always a no-op.

I found this issue via code inspection. It was introduced by commit
39f4cd9e99 ("xprtrdma: Harden chunk list encoding against send
buffer overflow"), but the code has changed enough since then that
this fix can't be automatically applied to stable.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2019-06-19 10:32:43 -04:00 committed by Anna Schumaker
parent 2d0abe36cf
commit 1310051c72
2 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/trace/events/rpcrdma.h
View File

@ -470,13 +470,12 @@ TRACE_DEFINE_ENUM(rpcrdma_replych);
TRACE_EVENT(xprtrdma_marshal,
TP_PROTO(
const struct rpc_rqst *rqst,
unsigned int hdrlen,
const struct rpcrdma_req *req,
unsigned int rtype,
unsigned int wtype
),
TP_ARGS(rqst, hdrlen, rtype, wtype),
TP_ARGS(req, rtype, wtype),
TP_STRUCT__entry(
__field(unsigned int, task_id)
@ -491,10 +490,12 @@ TRACE_EVENT(xprtrdma_marshal,
),
TP_fast_assign(
const struct rpc_rqst *rqst = &req->rl_slot;
__entry->task_id = rqst->rq_task->tk_pid;
__entry->client_id = rqst->rq_task->tk_client->cl_clid;
__entry->xid = be32_to_cpu(rqst->rq_xid);
__entry->hdrlen = hdrlen;
__entry->hdrlen = req->rl_hdrbuf.len;
__entry->headlen = rqst->rq_snd_buf.head[0].iov_len;
__entry->pagelen = rqst->rq_snd_buf.page_len;
__entry->taillen = rqst->rq_snd_buf.tail[0].iov_len;

6
net/sunrpc/xprtrdma/rpc_rdma.c
View File

@ -867,12 +867,12 @@ rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst)
if (ret)
goto out_err;
trace_xprtrdma_marshal(rqst, xdr_stream_pos(xdr), rtype, wtype);
ret = rpcrdma_prepare_send_sges(r_xprt, req, xdr_stream_pos(xdr),
ret = rpcrdma_prepare_send_sges(r_xprt, req, req->rl_hdrbuf.len,
&rqst->rq_snd_buf, rtype);
if (ret)
goto out_err;
trace_xprtrdma_marshal(req, rtype, wtype);
return 0;
out_err: