NFSD: fix use-after-free in __nfs42_ssc_open()

commit 75333d48f92256a0dec91dbf07835e804fc411c0 upstream.

Problem caused by source's vfsmount being unmounted but remains
on the delayed unmount list. This happens when nfs42_ssc_open()
return errors.

Fixed by removing nfsd4_interssc_connect(), leave the vfsmount
for the laundromat to unmount when idle time expires.

We don't need to call nfs_do_sb_deactive when nfs42_ssc_open
return errors since the file was not opened so nfs_server->active
was not incremented. Same as in nfsd4_copy, if we fail to
launch nfsd4_do_async_copy thread then there's no need to
call nfs_do_sb_deactive

Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
Tested-by: Xingyuan Mo <hdthky0@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 57af9c30eb48df632695e764eddacfa9da2214f1..b817d24d25a607eacc874f9a5a49dcbceed5c18c 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1351,13 +1351,6 @@ out_err:
        return status;
 }
 
-static void
-nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
-{
-       nfs_do_sb_deactive(ss_mnt->mnt_sb);
-       mntput(ss_mnt);
-}
-
 /*
  * Verify COPY destination stateid.
  *
@@ -1460,11 +1453,6 @@ nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct nfsd_file *src,
 {
 }
 
-static void
-nfsd4_interssc_disconnect(struct vfsmount *ss_mnt)
-{
-}
-
 static struct file *nfs42_ssc_open(struct vfsmount *ss_mnt,
                                   struct nfs_fh *src_fh,
                                   nfs4_stateid *stateid)
@@ -1622,14 +1610,14 @@ static int nfsd4_do_async_copy(void *data)
                copy->nf_src = kzalloc(sizeof(struct nfsd_file), GFP_KERNEL);
                if (!copy->nf_src) {
                        copy->nfserr = nfserr_serverfault;
-                       nfsd4_interssc_disconnect(copy->ss_mnt);
+                       /* ss_mnt will be unmounted by the laundromat */
                        goto do_callback;
                }
                copy->nf_src->nf_file = nfs42_ssc_open(copy->ss_mnt, &copy->c_fh,
                                              &copy->stateid);
                if (IS_ERR(copy->nf_src->nf_file)) {
                        copy->nfserr = nfserr_offload_denied;
-                       nfsd4_interssc_disconnect(copy->ss_mnt);
+                       /* ss_mnt will be unmounted by the laundromat */
                        goto do_callback;
                }
        }
@@ -1714,8 +1702,10 @@ out_err:
        if (async_copy)
                cleanup_async_copy(async_copy);
        status = nfserrno(-ENOMEM);
-       if (!copy->cp_intra)
-               nfsd4_interssc_disconnect(copy->ss_mnt);
+       /*
+        * source's vfsmount of inter-copy will be unmounted
+        * by the laundromat
+        */
        goto out;
 }