The netlink policy for IFLA_AMT_LOCAL_IP and IFLA_AMT_DISCOVERY_IP is an untyped entry with .len set to the size of an IPv4 address, which netlink validation treats as a minimum length only. Any longer payload passes, and nla_get_in_addr() then reads just its first four bytes: an iproute2 that puts a 16-byte IPv6 literal in one of these IPv4 attributes turns "2001:db8::" into 32.1.13.184, and the device is created with an address the user never asked for. Use NLA_POLICY_EXACT_LEN(sizeof(__be32)) for both, so every payload that is not exactly four bytes long is refused with a standard extack instead of being truncated. The range check this expands to fails the attribute even under the liberal parsing rtnetlink applies to IFLA_INFO_DATA. amt_get_size() and amt_fill_info() already emit exactly four bytes for these attributes. IFLA_AMT_REMOTE_IP is only ever reported, never read from a request, so it is left unchanged. Fixes: b9022b53adad ("amt: add control plane of amt interface") Assisted-by: LLM Signed-off-by: Omar Ramadan --- drivers/net/amt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/amt.c b/drivers/net/amt.c index e9b1a45..e466cf8 100644 --- a/drivers/net/amt.c +++ b/drivers/net/amt.c @@ -3201,9 +3201,9 @@ static const struct nla_policy amt_policy[IFLA_AMT_MAX + 1] = { [IFLA_AMT_RELAY_PORT] = { .type = NLA_U16 }, [IFLA_AMT_GATEWAY_PORT] = { .type = NLA_U16 }, [IFLA_AMT_LINK] = { .type = NLA_U32 }, - [IFLA_AMT_LOCAL_IP] = { .len = sizeof_field(struct iphdr, daddr) }, + [IFLA_AMT_LOCAL_IP] = NLA_POLICY_EXACT_LEN(sizeof(__be32)), [IFLA_AMT_REMOTE_IP] = { .len = sizeof_field(struct iphdr, daddr) }, - [IFLA_AMT_DISCOVERY_IP] = { .len = sizeof_field(struct iphdr, daddr) }, + [IFLA_AMT_DISCOVERY_IP] = NLA_POLICY_EXACT_LEN(sizeof(__be32)), [IFLA_AMT_MAX_TUNNELS] = { .type = NLA_U32 }, };