libceph: NULL deref on osdmap_apply_incremental() error path

There are hidden gotos in the ceph_decode_* macros.  We need to set the
"err" variable on these error paths otherwise we end up returning
ERR_PTR(0) which is NULL.  It causes NULL dereferences in the callers.

Fixes: 6f428df4 ("libceph: pg_upmap[_items] infrastructure")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[idryomov@gmail.com: similar bug in osdmap_decode(), changelog tweak]
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

net/ceph/osdmap.c

@@ -1544,7 +1544,7 @@ static int osdmap_decode(void **p, void *end, struct ceph_osdmap *map)
 	if (struct_v >= 3) {
 		/* erasure_code_profiles */
 		ceph_decode_skip_map_of_map(p, end, string, string, string,
-					    bad);
+					    e_inval);
 	}
 
 	if (struct_v >= 4) {
@@ -1825,9 +1825,9 @@ struct ceph_osdmap *osdmap_apply_incremental(void **p, void *end,
 	if (struct_v >= 3) {
 		/* new_erasure_code_profiles */
 		ceph_decode_skip_map_of_map(p, end, string, string, string,
-					    bad);
+					    e_inval);
 		/* old_erasure_code_profiles */
-		ceph_decode_skip_set(p, end, string, bad);
+		ceph_decode_skip_set(p, end, string, e_inval);
 	}
 
 	if (struct_v >= 4) {