ovn-sbctl: Prevent core dump from ovn-sbctl lflow-list [datpath] 0xflow

When ovn-sbctl lflow-list gets lflow argument with 0x prefix, e.g. 0x8131c8a8,
it prints correct output, but fails with coredump.
For example:
ovn-sbctl --uuid lflow-list sw1 0x8131c8a8

Datapath: "sw1" (4b1e53d8-9f0f-4768-b4a6-6cbc58a4bfda)  Pipeline: egress
    uuid=0x8131c8a8, table=10(ls_out_port_sec_l2 ), priority=100  ,
match=(eth.mcast), action=(output;)
free(): invalid pointer
[2]    616553 abort (core dumped)  ovn-sbctl --uuid dump-flows sw1 0x8131c8a8

 This patch fixes it.

Signed-off-by: Alexey Roytman <roytman@il.ibm.com>
Signed-off-by: Mark Michelson <mmichels@redhat.com>
Acked-by: Mark Michelson <mmichels@redhat.com>

tests/ovn-sbctl.at

@@ -148,3 +148,11 @@ inactivity_probe    : 30000
 
 OVN_SBCTL_TEST_STOP
 AT_CLEANUP
+
+AT_SETUP([ovn-sbctl - invalid 0x flow])
+OVN_SBCTL_TEST_START
+
+check ovn-sbctl lflow-list 0x12345678
+
+OVN_SBCTL_TEST_STOP
+AT_CLEANUP

utilities/ovn-sbctl.c

@@ -763,23 +763,28 @@ sbctl_lflow_cmp(const void *a_, const void *b_)
             : strcmp(a->match, b->match));
 }
 
-static char *
+static bool
+is_uuid_with_prefix(const char *uuid)
+{
+     return uuid[0] == '0' && (uuid[1] == 'x' || uuid[1] == 'X');
+}
+
+static bool
 parse_partial_uuid(char *s)
 {
     /* Accept a full or partial UUID. */
     if (uuid_is_partial_string(s)) {
-        return s;
+        return true;
     }
 
     /* Accept a full or partial UUID prefixed by 0x, since "ovs-ofctl
      * dump-flows" prints cookies prefixed by 0x. */
-    if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')
-        && uuid_is_partial_string(s + 2)) {
-        return s + 2;
+    if (is_uuid_with_prefix(s) && uuid_is_partial_string(s + 2)) {
+        return true;
     }
 
     /* Not a (partial) UUID. */
-    return NULL;
+    return false;
 }
 
 static const char *
@@ -798,8 +803,11 @@ is_partial_uuid_match(const struct uuid *uuid, const char *match)
      * from UUIDs, and cookie values are printed without leading zeros because
      * they're just numbers. */
     const char *s1 = strip_leading_zero(uuid_s);
-    const char *s2 = strip_leading_zero(match);
-
+    const char *s2 = match;
+    if (is_uuid_with_prefix(s2)) {
+        s2 = s2 + 2;
+    }
+    s2 = strip_leading_zero(s2);
     return !strncmp(s1, s2, strlen(s2));
 }
 
@@ -1133,12 +1141,10 @@ cmd_lflow_list(struct ctl_context *ctx)
     }
 
     for (size_t i = 1; i < ctx->argc; i++) {
-        char *s = parse_partial_uuid(ctx->argv[i]);
-        if (!s) {
+        if (!parse_partial_uuid(ctx->argv[i])) {
             ctl_fatal("%s is not a UUID or the beginning of a UUID",
                       ctx->argv[i]);
         }
-        ctx->argv[i] = s;
     }
 
     struct vconn *vconn = sbctl_open_vconn(&ctx->options);