avoid NULL pointers in discovery code

Both sysfs_pathinfo() and path_offline() could hit NULL pointers when
trying to dereference the newly acquired parent sysfs_device.  By being
more defensive a crash I experienced in path_offline() is avoided.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index 7d9f299..98d1618 100644 (file)
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -589,11 +589,17 @@ path_offline (struct path * pp)
                condlog(1, "%s: failed to get sysfs information", pp->dev);
                return 1;
        }
+
        parent = sysfs_device_get_parent(pp->sysdev);
        if (!parent)
                parent = pp->sysdev;
-       if (!strncmp(parent->kernel, "block",5))
+       if (parent && !strncmp(parent->kernel, "block",5))
                parent = sysfs_device_get_parent(parent);
+       if (!parent) {
+               condlog(1, "%s: failed to get parent", pp->dev);
+               return 1;
+       }
+
        if (sysfs_get_state(parent, buff, SCSI_STATE_SIZE))
                return 1;
 
@@ -624,9 +630,12 @@ sysfs_pathinfo(struct path * pp)
        parent = sysfs_device_get_parent(pp->sysdev);
        if (!parent)
                parent = pp->sysdev;
-
-       if (!strncmp(parent->kernel, "block",5))
+       if (parent && !strncmp(parent->kernel, "block",5))
                parent = sysfs_device_get_parent(parent);
+       if (!parent) {
+               condlog(1, "%s: failed to get parent", pp->dev);
+               return 1;
+       }
 
        if (!strncmp(pp->dev,"cciss",5))
                strcpy(parent->subsystem,"cciss");