From bb29dd84333a96f309c6d0f88b285b5b78927058 Mon Sep 17 00:00:00 2001 From: Anna Schumaker Date: Wed, 26 Oct 2016 10:33:31 -0400 Subject: [PATCH] SUNRPC: Fix suspicious RCU usage We need to hold the rcu_read_lock() when calling rcu_dereference(), otherwise we can't guarantee that the object being dereferenced still exists. Fixes: 39e5d2df ("SUNRPC search xprt switch for sockaddr") Signed-off-by: Anna Schumaker --- net/sunrpc/clnt.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 34dd7b26ee5f..62a482790937 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -2753,14 +2753,18 @@ EXPORT_SYMBOL_GPL(rpc_cap_max_reconnect_timeout); void rpc_clnt_xprt_switch_put(struct rpc_clnt *clnt) { + rcu_read_lock(); xprt_switch_put(rcu_dereference(clnt->cl_xpi.xpi_xpswitch)); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_put); void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt) { + rcu_read_lock(); rpc_xprt_switch_add_xprt(rcu_dereference(clnt->cl_xpi.xpi_xpswitch), xprt); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_add_xprt); @@ -2770,9 +2774,8 @@ bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt, struct rpc_xprt_switch *xps; bool ret; - xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch); - rcu_read_lock(); + xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch); ret = rpc_xprt_switch_has_addr(xps, sap); rcu_read_unlock(); return ret;