From: Anna Schumaker <Anna.Schumaker@Netapp.com>
Date: Thu, 28 Oct 2021 15:17:41 -0400
Subject: [PATCH] SUNRPC: Check if the xprt is connected before handling sysfs
 reads
Git-commit: 17f09d3f619a7ad2d2b021b4e5246f08225b1b0f
Patch-mainline: v5.16
References: bsc#1194324

xprts don't immediately reconnect when changing the "dstaddr" property,
instead this gets handled the next time an operation uses the transport.
This could lead to NULL pointer dereferences when trying to read sysfs
files between the disconnect and reconnect operations. Fix this by
returning an error if the xprt is not connected.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 net/sunrpc/sysfs.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -107,8 +107,10 @@ static ssize_t rpc_sysfs_xprt_info_show(
 	struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
 	ssize_t ret;
 
-	if (!xprt)
-		return 0;
+	if (!xprt || !xprt_connected(xprt)) {
+		xprt_put(xprt);
+		return -ENOTCONN;
+	}
 
 	ret = sprintf(buf, "last_used=%lu\ncur_cong=%lu\ncong_win=%lu\n"
 		       "max_num_slots=%u\nmin_num_slots=%u\nnum_reqs=%u\n"