The patch below does not apply to the 5.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From bdb2ce82818577ba6e57b7d68b698b8d17329281 Mon Sep 17 00:00:00 2001

From: Chuck Lever chuck.lever@oracle.com Date: Sun, 19 Apr 2020 20:03:05 -0400 Subject: [PATCH] xprtrdma: Fix trace point use-after-free race

It's not safe to use resources pointed to by the @send_wr of ib_post_send() _after_ that function returns. Those resources are typically freed by the Send completion handler, which can run before ib_post_send() returns.

Thus the trace points currently around ib_post_send() in the client's RPC/RDMA transport are a hazard, even when they are disabled. Rearrange them so that they touch the Work Request only _before_ ib_post_send() is invoked.

Fixes: ab03eff58eb5 ("xprtrdma: Add trace points in RPC Call transmit paths") Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com

diff --git a/include/trace/events/rpcrdma.h b/include/trace/events/rpcrdma.h index 051f26fedc4d..72f043876019 100644 --- a/include/trace/events/rpcrdma.h +++ b/include/trace/events/rpcrdma.h @@ -692,11 +692,10 @@ TRACE_EVENT(xprtrdma_prepsend_failed,

TRACE_EVENT(xprtrdma_post_send, TP_PROTO( - const struct rpcrdma_req *req, - int status + const struct rpcrdma_req *req ),

- TP_ARGS(req, status), + TP_ARGS(req),

TP_STRUCT__entry( __field(const void *, req) @@ -705,7 +704,6 @@ TRACE_EVENT(xprtrdma_post_send, __field(unsigned int, client_id) __field(int, num_sge) __field(int, signaled) - __field(int, status) ),

TP_fast_assign( @@ -718,15 +716,13 @@ TRACE_EVENT(xprtrdma_post_send, __entry->sc = req->rl_sendctx; __entry->num_sge = req->rl_wr.num_sge; __entry->signaled = req->rl_wr.send_flags & IB_SEND_SIGNALED; - __entry->status = status; ),

- TP_printk("task:%u@%u req=%p sc=%p (%d SGE%s) %sstatus=%d", + TP_printk("task:%u@%u req=%p sc=%p (%d SGE%s) %s", __entry->task_id, __entry->client_id, __entry->req, __entry->sc, __entry->num_sge, (__entry->num_sge == 1 ? "" : "s"), - (__entry->signaled ? "signaled " : ""), - __entry->status + (__entry->signaled ? "signaled" : "") ) );

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 29ae982d69cf..05c4d3a9cda2 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -1356,8 +1356,8 @@ int rpcrdma_post_sends(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req) --ep->re_send_count; }

+ trace_xprtrdma_post_send(req); rc = frwr_send(r_xprt, req); - trace_xprtrdma_post_send(req, rc); if (rc) return -ENOTCONN; return 0;