pnfs/flexfiles: Fix PTR_ERR() dereferences in ff_layout_track_ds_error

BugLink: https://bugs.launchpad.net/bugs/1839036
commit 8e04fdfadda75a849c649f7e50fe7d97772e1fcb upstream.

mirror->mirror_ds can be NULL if uninitialised, but can contain
a PTR_ERR() if call to GETDEVICEINFO failed.

Fixes: 65990d1afbd2 ("pNFS/flexfiles: Fix a deadlock on LAYOUTGET")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: stable@vger.kernel.org # 4.10+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index 2de6e87e5ee50205e3f8d5f3722b47240fd4041e..2464b9b80698899d1d11aaf5bf7568de5be7aeef 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -306,7 +306,7 @@ int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
        if (status == 0)
                return 0;
 
-       if (mirror->mirror_ds == NULL)
+       if (IS_ERR_OR_NULL(mirror->mirror_ds))
                return -EINVAL;
 
        dserr = kmalloc(sizeof(*dserr), gfp_flags);