Fix udevd SECLABEL token parsing

The udevd rules parsing rewrite in v243 broke SECLABEL parsing,
with the result being that udevd crashes when it parses a line
containing a SECLABEL token. Fix the handling of the attribute
of SECLABEL tokens when parsing, and add a check to prevent
crashes if the attribute is missing.

Upstream-Status: Pending

Signed-off-by: Scott Murray <scott.murray@konsulko.com>

diff --git a/src/udev/udev-rules.c b/src/udev/udev-rules.c
index efea16e5c5..3e757ccb06 100644
--- a/src/udev/udev-rules.c
+++ b/src/udev/udev-rules.c
@@ -918,7 +918,7 @@ static int parse_token(UdevRules *rules, const char *key, char *attr, UdevRuleOp
                         op = OP_ASSIGN;
                 }
 
-                r = rule_line_add_token(rule_line, TK_A_SECLABEL, op, value, NULL);
+                r = rule_line_add_token(rule_line, TK_A_SECLABEL, op, value, attr);
         } else if (streq(key, "RUN")) {
                 if (is_match || op == OP_REMOVE)
                         return log_token_invalid_op(rules, key);
@@ -1927,6 +1927,8 @@ static int udev_rule_apply_token_to_event(
                 _cleanup_free_ char *name = NULL, *label = NULL;
                 char label_str[UTIL_LINE_SIZE] = {};
 
+                if (!token->data)
+                        break;
                 name = strdup((const char*) token->data);
                 if (!name)
                         return log_oom();