net: unix: fix inflight counting bug in garbage collector

[linux-2.6-omap-h63xx.git] / net / unix / af_unix.c

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 4d3c6071b9a47102212bcc65afa55c640e7bb5b8..eb90f77bb0e294b6358db3361740deaa0bec969e 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1302,14 +1302,23 @@ static void unix_destruct_fds(struct sk_buff *skb)
        sock_wfree(skb);
 }
 
-static void unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
+static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 {
        int i;
+
+       /*
+        * Need to duplicate file references for the sake of garbage
+        * collection.  Otherwise a socket in the fps might become a
+        * candidate for GC while the skb is not yet queued.
+        */
+       UNIXCB(skb).fp = scm_fp_dup(scm->fp);
+       if (!UNIXCB(skb).fp)
+               return -ENOMEM;
+
        for (i=scm->fp->count-1; i>=0; i--)
                unix_inflight(scm->fp->fp[i]);
-       UNIXCB(skb).fp = scm->fp;
        skb->destructor = unix_destruct_fds;
-       scm->fp = NULL;
+       return 0;
 }
 
 /*
@@ -1368,8 +1377,11 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
                goto out;
 
        memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
-       if (siocb->scm->fp)
-               unix_attach_fds(siocb->scm, skb);
+       if (siocb->scm->fp) {
+               err = unix_attach_fds(siocb->scm, skb);
+               if (err)
+                       goto out_free;
+       }
        unix_get_secdata(siocb->scm, skb);
 
        skb_reset_transport_header(skb);
@@ -1538,8 +1550,13 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                size = min_t(int, size, skb_tailroom(skb));
 
                memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
-               if (siocb->scm->fp)
-                       unix_attach_fds(siocb->scm, skb);
+               if (siocb->scm->fp) {
+                       err = unix_attach_fds(siocb->scm, skb);
+                       if (err) {
+                               kfree_skb(skb);
+                               goto out_err;
+                       }
+               }
 
                if ((err = memcpy_fromiovec(skb_put(skb,size), msg->msg_iov, size)) != 0) {
                        kfree_skb(skb);