From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Sun, 30 Sep 2018 11:23:58 +0000 (+0900)
Subject: dhcp6: check option length before reading values
X-Git-Tag: v240~640^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=84452783b8bcc44e0dbb7fa6ddc6dad8c064bdfe;p=thirdparty%2Fsystemd.git

dhcp6: check option length before reading values

Fixes oss-fuzz#10746
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10746.
---

diff --git a/src/libsystemd-network/dhcp6-internal.h b/src/libsystemd-network/dhcp6-internal.h
index c45b068fd7c..63d8fe35f80 100644
--- a/src/libsystemd-network/dhcp6-internal.h
+++ b/src/libsystemd-network/dhcp6-internal.h
@@ -89,7 +89,7 @@ int dhcp6_option_append_pd(uint8_t *buf, size_t len, DHCP6IA *pd);
 int dhcp6_option_append_fqdn(uint8_t **buf, size_t *buflen, const char *fqdn);
 int dhcp6_option_parse(uint8_t **buf, size_t *buflen, uint16_t *optcode,
                        size_t *optlen, uint8_t **optvalue);
-int dhcp6_option_parse_status(DHCP6Option *option);
+int dhcp6_option_parse_status(DHCP6Option *option, size_t len);
 int dhcp6_option_parse_ia(DHCP6Option *iaoption, DHCP6IA *ia);
 int dhcp6_option_parse_ip6addrs(uint8_t *optval, uint16_t optlen,
                                 struct in6_addr **addrs, size_t count,
diff --git a/src/libsystemd-network/dhcp6-option.c b/src/libsystemd-network/dhcp6-option.c
index 05f589e911c..cf19d366d3b 100644
--- a/src/libsystemd-network/dhcp6-option.c
+++ b/src/libsystemd-network/dhcp6-option.c
@@ -247,10 +247,11 @@ int dhcp6_option_parse(uint8_t **buf, size_t *buflen, uint16_t *optcode,
         return 0;
 }
 
-int dhcp6_option_parse_status(DHCP6Option *option) {
+int dhcp6_option_parse_status(DHCP6Option *option, size_t len) {
         DHCP6StatusOption *statusopt = (DHCP6StatusOption *)option;
 
-        if (be16toh(option->len) + sizeof(DHCP6Option) < sizeof(*statusopt))
+        if (len < sizeof(DHCP6StatusOption) ||
+            be16toh(option->len) + sizeof(DHCP6Option) < sizeof(DHCP6StatusOption))
                 return -ENOBUFS;
 
         return be16toh(statusopt->status);
@@ -277,7 +278,7 @@ static int dhcp6_option_parse_address(DHCP6Option *option, DHCP6IA *ia,
         }
 
         if (be16toh(option->len) + sizeof(DHCP6Option) > sizeof(*addr_option)) {
-                r = dhcp6_option_parse_status((DHCP6Option *)addr_option->options);
+                r = dhcp6_option_parse_status((DHCP6Option *)addr_option->options, be16toh(option->len) + sizeof(DHCP6Option) - sizeof(*addr_option));
                 if (r != 0)
                         return r < 0 ? r: 0;
         }
@@ -317,7 +318,7 @@ static int dhcp6_option_parse_pdprefix(DHCP6Option *option, DHCP6IA *ia,
         }
 
         if (be16toh(option->len) + sizeof(DHCP6Option) > sizeof(*pdprefix_option)) {
-                r = dhcp6_option_parse_status((DHCP6Option *)pdprefix_option->options);
+                r = dhcp6_option_parse_status((DHCP6Option *)pdprefix_option->options, be16toh(option->len) + sizeof(DHCP6Option) - sizeof(*pdprefix_option));
                 if (r != 0)
                         return r < 0 ? r: 0;
         }
@@ -462,7 +463,7 @@ int dhcp6_option_parse_ia(DHCP6Option *iaoption, DHCP6IA *ia) {
 
                 case SD_DHCP6_OPTION_STATUS_CODE:
 
-                        status = dhcp6_option_parse_status(option);
+                        status = dhcp6_option_parse_status(option, optlen);
                         if (status) {
                                 log_dhcp6_client(client, "IA status %d",
                                                  status);
diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index 47a474395f4..9b9e9610e48 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -900,7 +900,7 @@ static int client_parse_message(
                         break;
 
                 case SD_DHCP6_OPTION_STATUS_CODE:
-                        status = dhcp6_option_parse_status(option);
+                        status = dhcp6_option_parse_status(option, optlen);
                         if (status) {
                                 log_dhcp6_client(client, "%s Status %s",
                                                  dhcp6_message_type_to_string(message->type),