libceph: fix crush_decode() call site in osdmap_decode()

The size of the memory area feeded to crush_decode() should be limited
not only by osdmap end, but also by the crush map length.  Also, drop
unnecessary dout() (dout() in crush_decode() conveys the same info) and
step past crush map only if it is decoded successfully.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index c39ac62..d4a6b0d 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -802,16 +802,13 @@
 
 	/* crush */
 	ceph_decode_32_safe(p, end, len, e_inval);
-	dout("osdmap_decode crush len %d from off 0x%x\n", len,
-	     (int)(*p - start));
-	ceph_decode_need(p, end, len, e_inval);
-	map->crush = crush_decode(*p, end);
-	*p += len;
+	map->crush = crush_decode(*p, min(*p + len, end));
 	if (IS_ERR(map->crush)) {
 		err = PTR_ERR(map->crush);
 		map->crush = NULL;
 		goto bad;
 	}
+	*p += len;
 
 	/* ignore the rest */
 	*p = end;