netlink: Fix assert condition on n_containers

(cherry picked from commit 179b4db439ce4c41d44a6b5de22244c9ab54b252)

diff --git a/src/libsystemd/sd-netlink/netlink-message.c b/src/libsystemd/sd-netlink/netlink-message.c
index 39e3c36ad2aba25246b0535c6f80b7af268b698b..2648b338f5daa3afacb25b0c5ededd55cdc37dad 100644 (file)
--- a/src/libsystemd/sd-netlink/netlink-message.c
+++ b/src/libsystemd/sd-netlink/netlink-message.c
@@ -15,8 +15,7 @@
 #include "socket-util.h"
 #include "strv.h"
 
-#define GET_CONTAINER(m, i) ((i) < (m)->n_containers ? (struct rtattr*)((uint8_t*)(m)->hdr + (m)->containers[i].offset) : NULL)
-#define PUSH_CONTAINER(m, new) (m)->container_offsets[(m)->n_containers++] = (uint8_t*)(new) - (uint8_t*)(m)->hdr;
+#define GET_CONTAINER(m, i) ((struct rtattr*)((uint8_t*)(m)->hdr + (m)->containers[i].offset))
 
 #define RTA_TYPE(rta) ((rta)->rta_type & NLA_TYPE_MASK)
 #define RTA_FLAGS(rta) ((rta)->rta_type & ~NLA_TYPE_MASK)
@@ -452,7 +451,8 @@ int sd_netlink_message_open_container(sd_netlink_message *m, unsigned short type
 
         assert_return(m, -EINVAL);
         assert_return(!m->sealed, -EPERM);
-        assert_return(m->n_containers < RTNL_CONTAINER_DEPTH, -ERANGE);
+        /* m->containers[m->n_containers + 1] is accessed both in read and write. Prevent access out of bound */
+        assert_return(m->n_containers < (RTNL_CONTAINER_DEPTH - 1), -ERANGE);
 
         r = message_attribute_has_type(m, &size, type, NETLINK_TYPE_NESTED);
         if (r < 0) {
@@ -499,6 +499,7 @@ int sd_netlink_message_open_container_union(sd_netlink_message *m, unsigned shor
 
         assert_return(m, -EINVAL);
         assert_return(!m->sealed, -EPERM);
+        assert_return(m->n_containers < (RTNL_CONTAINER_DEPTH - 1), -ERANGE);
 
         r = type_system_get_type_system_union(m->containers[m->n_containers].type_system, &type_system_union, type);
         if (r < 0)
@@ -541,6 +542,7 @@ int sd_netlink_message_open_array(sd_netlink_message *m, uint16_t type) {
 
         assert_return(m, -EINVAL);
         assert_return(!m->sealed, -EPERM);
+        assert_return(m->n_containers < (RTNL_CONTAINER_DEPTH - 1), -ERANGE);
 
         r = add_rtattr(m, type | NLA_F_NESTED, NULL, 0);
         if (r < 0)
@@ -939,7 +941,7 @@ int sd_netlink_message_enter_container(sd_netlink_message *m, unsigned short typ
         int r;
 
         assert_return(m, -EINVAL);
-        assert_return(m->n_containers < RTNL_CONTAINER_DEPTH, -EINVAL);
+        assert_return(m->n_containers < (RTNL_CONTAINER_DEPTH - 1), -EINVAL);
 
         r = type_system_get_type(m->containers[m->n_containers].type_system,
                                  &nl_type,
@@ -1030,7 +1032,7 @@ int sd_netlink_message_enter_array(sd_netlink_message *m, unsigned short type_id
         int r;
 
         assert_return(m, -EINVAL);
-        assert_return(m->n_containers < RTNL_CONTAINER_DEPTH, -EINVAL);
+        assert_return(m->n_containers < (RTNL_CONTAINER_DEPTH - 1), -EINVAL);
 
         r = netlink_message_read_internal(m, type_id, &container, NULL);
         if (r < 0)