ofp-prop: Fix unaligned 128 bit access.

When compiling with '-fsanitize=address,undefined', the "ovs-ofctl
ct-flush" test will yield the following undefined behavior flagged by
UBSan. This problem is caused by the fact that 128bit property put/parse
functions weren't adding appropriate padding before writing or reading
the value.

This patch uses get_32aligned_* functions to copy the bytes as they are
aligned.

 lib/ofp-prop.c:277:14: runtime error: load of misaligned address
 0x60600000687c for type 'union ovs_be128', which requires 8 byte
 alignment
 0x60600000687c: note: pointer points here
  00 05 00 14 00 00 00 00  00 00 00 00 00 00 00 00  00 ff ab 00
              ^
    0: in ofpprop_parse_u128 lib/ofp-prop.c:277
    1: in ofp_ct_match_decode lib/ofp-ct.c:525
    2: in ofp_print_nxt_ct_flush lib/ofp-print.c:959
    3: in ofp_to_string__ lib/ofp-print.c:1206
    4: in ofp_to_string lib/ofp-print.c:1264
    5: in ofp_print lib/ofp-print.c:1308
    6: in ofctl_ofp_print utilities/ovs-ofctl.c:4899
    7: in ovs_cmdl_run_command__ lib/command-line.c:247
    8: in ovs_cmdl_run_command lib/command-line.c:278
    9: in main utilities/ovs-ofctl.c:186

Fixes: 62c5d32 ("ofp-prop: Add helper for parsing and storing of ovs_u128.")
Acked-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Mike Pattrick <mkp@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

lib/ofp-prop.c

@@ -21,6 +21,7 @@
 #include "openvswitch/ofp-errors.h"
 #include "openvswitch/ofp-prop.h"
 #include "openvswitch/vlog.h"
+#include "unaligned.h"
 #include "util.h"
 #include "uuid.h"
 
@@ -190,11 +191,12 @@ ofpprop_parse_be64(const struct ofpbuf *property, ovs_be64 *value)
 enum ofperr
 ofpprop_parse_be128(const struct ofpbuf *property, ovs_be128 *value)
 {
-    ovs_be128 *p = property->msg;
+    ovs_32aligned_be128 *p = property->msg;
+
     if (ofpbuf_msgsize(property) != sizeof *p) {
         return OFPERR_OFPBPC_BAD_LEN;
     }
-    *value = *p;
+    *value = get_32aligned_be128(p);
     return 0;
 }
 
@@ -270,12 +272,13 @@ ofpprop_parse_u64(const struct ofpbuf *property, uint64_t *value)
 enum ofperr
 ofpprop_parse_u128(const struct ofpbuf *property, ovs_u128 *value)
 {
-    ovs_be128 *p = property->msg;
-    if (ofpbuf_msgsize(property) != sizeof *p) {
-        return OFPERR_OFPBPC_BAD_LEN;
+    enum ofperr error = ofpprop_parse_be128(property, (ovs_be128 *) value);
+
+    if (!error) {
+        *value = ntoh128(*(ovs_be128 *) value);
     }
-    *value = ntoh128(*p);
-    return 0;
+
+    return error;
 }
 
 /* Attempts to parse 'property' as a property containing a UUID.  If