linux-kernel - [PATCH 5.15 134/244] net/sunrpc: fix potential memory leaks in rpc_sysfs_xprt_state

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Date:   Tue, 23 Aug 2022 10:24:53 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xin Xiong <xiongx18@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.15 134/244] net/sunrpc: fix potential memory leaks in rpc_sysfs_xprt_state_change()

From: Xin Xiong <xiongx18@...an.edu.cn>

commit bfc48f1b0505ffcb03a6d749139b7577d6b81ae0 upstream.

The issue happens on some error handling paths. When the function
fails to grab the object `xprt`, it simply returns 0, forgetting to
decrease the reference count of another object `xps`, which is
increased by rpc_sysfs_xprt_kobj_get_xprt_switch(), causing refcount
leaks. Also, the function forgets to check whether `xps` is valid
before using it, which may result in NULL-dereferencing issues.

Fix it by adding proper error handling code when either `xprt` or
`xps` is NULL.

Fixes: 5b7eb78486cd ("SUNRPC: take a xprt offline using sysfs")
Signed-off-by: Xin Xiong <xiongx18@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/sunrpc/sysfs.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -282,8 +282,10 @@ static ssize_t rpc_sysfs_xprt_state_chan
 	int offline = 0, online = 0, remove = 0;
 	struct rpc_xprt_switch *xps = rpc_sysfs_xprt_kobj_get_xprt_switch(kobj);
 
-	if (!xprt)
-		return 0;
+	if (!xprt || !xps) {
+		count = 0;
+		goto out_put;
+	}
 
 	if (!strncmp(buf, "offline", 7))
 		offline = 1;