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From:   Artur Molchanov <arturmolchanov@gmail.com>
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Subject: [PATCH v2] net/sunrpc: Fix return value for sysctl sunrpc.transports
Message-Id: <20C3D746-91F5-45E1-B105-0A1B1ABAA9BB@gmail.com>
Date:   Mon, 12 Oct 2020 01:00:45 +0300
Cc:     linux-nfs@vger.kernel.org
To:     bfields@fieldses.org, chuck.lever@oracle.com
Precedence: bulk

Fix returning value for sysctl sunrpc.transports.
Return error code from sysctl proc_handler function proc_do_xprt instead =
of number of the written bytes.
Otherwise sysctl returns random garbage for this key.

Since v1:
- Handle negative returned value from memory_read_from_buffer as an =
error


Signed-off-by: Artur Molchanov <arturmolchanov@gmail.com>
Cc: stable@vger.kernel.org
---
 net/sunrpc/sysctl.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index 999eee1ed61c..e81a28f30f1d 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -70,7 +70,13 @@ static int proc_do_xprt(struct ctl_table *table, int =
write,
 		return 0;
 	}
 	len =3D svc_print_xprts(tmpbuf, sizeof(tmpbuf));
-	return memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, =
len);
+	*lenp =3D memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, =
len);
+
+	if (*lenp < 0) {
+		*lenp =3D 0;
+		return -EINVAL;
+	}
+	return 0;
 }
=20
 static int
--=20
2.20.1