netlink: Fix for potential crash parsing a flowtable

Kernel's flowtable message might not contain the
NFTA_FLOWTABLE_HOOK_DEVS attribute. In that case, nftnl_flowtable_get()
will return NULL for the respective nftnl attribute.

Fixes: db0697ce7f602 ("src: support for flowtable listing")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/src/netlink.c b/src/netlink.c
index bed816af3123d08586fbda62c3fdec5bc07c3307..0e0d32b846d6a85b51fed5cd3cd55e1aac4fc89c 100644 (file)
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -1847,7 +1847,7 @@ netlink_delinearize_flowtable(struct netlink_ctx *ctx,
        if (nftnl_flowtable_is_set(nlo, NFTNL_FLOWTABLE_FLAGS))
                flowtable->flags = nftnl_flowtable_get_u32(nlo, NFTNL_FLOWTABLE_FLAGS);
        dev_array = nftnl_flowtable_get(nlo, NFTNL_FLOWTABLE_DEVICES);
-       while (dev_array[len])
+       while (dev_array && dev_array[len])
                len++;
 
        if (len)