net/sunrpc: fix potential memory leaks in rpc_sysfs_xprt_state_change()

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@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
index 326a314..a7020b1 100644 (file)
--- a/net/sunrpc/sysfs.c
+++ b/net/sunrpc/sysfs.c
@@ -282,8 +282,10 @@ static ssize_t rpc_sysfs_xprt_state_change(struct kobject *kobj,
        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;