ceph: fix decoding of pool snap info

The pool info contains a vector for snap_info_t, not snap ids.  This fixes
the broken decoding, which would declare teh update corrupt when a pool
snapshot was created.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/osdmap.c

@@ -424,12 +424,30 @@ static void __remove_pg_pool(struct rb_root *root, struct ceph_pg_pool_info *pi)
 	kfree(pi);
 }
 
-static void __decode_pool(void **p, struct ceph_pg_pool_info *pi)
+static int __decode_pool(void **p, void *end, struct ceph_pg_pool_info *pi)
 {
+	unsigned n, m;
+
 	ceph_decode_copy(p, &pi->v, sizeof(pi->v));
 	calc_pg_masks(pi);
-	*p += le32_to_cpu(pi->v.num_snaps) * sizeof(u64);
+
+	/* num_snaps * snap_info_t */
+	n = le32_to_cpu(pi->v.num_snaps);
+	while (n--) {
+		ceph_decode_need(p, end, sizeof(u64) + 1 + sizeof(u64) +
+				 sizeof(struct ceph_timespec), bad);
+		*p += sizeof(u64) +       /* key */
+			1 + sizeof(u64) + /* u8, snapid */
+			sizeof(struct ceph_timespec);
+		m = ceph_decode_32(p);    /* snap name */
+		*p += m;
+	}
+
 	*p += le32_to_cpu(pi->v.num_removed_snap_intervals) * sizeof(u64) * 2;
+	return 0;
+
+bad:
+	return -EINVAL;
 }
 
 static int __decode_pool_names(void **p, void *end, struct ceph_osdmap *map)
@@ -571,7 +589,9 @@ struct ceph_osdmap *osdmap_decode(void **p, void *end)
 			kfree(pi);
 			goto bad;
 		}
-		__decode_pool(p, pi);
+		err = __decode_pool(p, end, pi);
+		if (err < 0)
+			goto bad;
 		__insert_pg_pool(&map->pg_pools, pi);
 	}
 
@@ -760,7 +780,9 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 			pi->id = pool;
 			__insert_pg_pool(&map->pg_pools, pi);
 		}
-		__decode_pool(p, pi);
+		err = __decode_pool(p, end, pi);
+		if (err < 0)
+			goto bad;
 	}
 	if (version >= 5 && __decode_pool_names(p, end, map) < 0)
 		goto bad;