SUNRPC: Switch one_sock_name() to use snprintf()

Use snprintf() in one_sock_name() to prevent overflowing the output
buffer.  If the name doesn't fit in the buffer, the buffer is filled
in with an empty string, and -ENAMETOOLONG is returned.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 18 insertions, 7 deletions

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 032b52ea9541..61d4a3281f94 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -240,22 +240,27 @@ out:
 /*
  * Report socket names for nfsdfs
  */
-static int one_sock_name(char *buf, struct svc_sock *svsk)
+static int svc_one_sock_name(struct svc_sock *svsk, char *buf, int remaining)
 {
         int len;
 
         switch(svsk->sk_sk->sk_family) {
-        case AF_INET:
-                len = sprintf(buf, "ipv4 %s %pI4 %d\n",
+        case PF_INET:
+                len = snprintf(buf, remaining, "ipv4 %s %pI4 %d\n",
                               svsk->sk_sk->sk_protocol == IPPROTO_UDP ?
                               "udp" : "tcp",
                               &inet_sk(svsk->sk_sk)->rcv_saddr,
                               inet_sk(svsk->sk_sk)->num);
                 break;
         default:
-                len = sprintf(buf, "*unknown-%d*\n",
+                len = snprintf(buf, remaining, "*unknown-%d*\n",
                                svsk->sk_sk->sk_family);
         }
+
+        if (len >= remaining) {
+                *buf = '\0';
+                return -ENAMETOOLONG;
+        }
         return len;
 }
 
@@ -282,15 +287,21 @@ int svc_sock_names(struct svc_serv *serv, char *buf, const size_t buflen,
 
         if (!serv)
                 return 0;
+
         spin_lock_bh(&serv->sv_lock);
         list_for_each_entry(svsk, &serv->sv_permsocks, sk_xprt.xpt_list) {
-                int onelen = one_sock_name(buf+len, svsk);
-                if (toclose && strcmp(toclose, buf+len) == 0)
+                int onelen = svc_one_sock_name(svsk, buf + len, buflen - len);
+                if (onelen < 0) {
+                        len = onelen;
+                        break;
+                }
+                if (toclose && strcmp(toclose, buf + len) == 0)
                         closesk = svsk;
                 else
                         len += onelen;
         }
         spin_unlock_bh(&serv->sv_lock);
+
         if (closesk)
                 /* Should unregister with portmap, but you cannot
                  * unregister just one protocol...
@@ -1195,7 +1206,7 @@ int svc_addsock(struct svc_serv *serv, const int fd, char *name_return,
                 sockfd_put(so);
                 return err;
         }
-        return one_sock_name(name_return, svsk);
+        return svc_one_sock_name(svsk, name_return, len);
 }
 EXPORT_SYMBOL_GPL(svc_addsock);