From: Xiang Mei <xmei5@asu.edu>
To: Andrew Lunn <andrew+netdev@lunn.ch>,
"David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Roopa Prabhu <roopa@nvidia.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Petr Machata <petrm@nvidia.com>, Andy Roulin <aroulin@nvidia.com>,
David Yang <mmyangfl@gmail.com>, Kees Cook <kees@kernel.org>,
Weiming Shi <bestswngs@gmail.com>, Xiang Mei <xmei5@asu.edu>
Subject: [PATCH net] vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes
Date: Sat, 4 Jul 2026 15:22:54 -0700 [thread overview]
Message-ID: <20260704222254.914567-1-xmei5@asu.edu> (raw)
The VXLAN VNI filter entry policy declares the GROUP/GROUP6 address
attributes as NLA_BINARY with only a maximum length, so validate_nla()
accepts a payload shorter than the address. The GROUP consumer reads it
with nla_get_in_addr(), an unconditional 4-byte load, so a short
attribute over-reads up to 3 bytes of uninitialised slab data, which are
stored into remote_ip and echoed back via RTM_GETTUNNEL, disclosing
kernel memory.
Switch both entries to NLA_POLICY_EXACT_LEN() so the validator rejects
any GROUP/GROUP6 that is not exactly 4 / 16 bytes; a valid address is
always sent at full width.
Fixes: f9c4bb0b245c ("vxlan: vni filtering support on collect metadata device")
Reported-by: Weiming Shi <bestswngs@gmail.com>
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Xiang Mei <xmei5@asu.edu>
---
drivers/net/vxlan/vxlan_vnifilter.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/net/vxlan/vxlan_vnifilter.c b/drivers/net/vxlan/vxlan_vnifilter.c
index 3e76f4e21094..dd94085e0886 100644
--- a/drivers/net/vxlan/vxlan_vnifilter.c
+++ b/drivers/net/vxlan/vxlan_vnifilter.c
@@ -462,10 +462,8 @@ static int vxlan_vnifilter_dump(struct sk_buff *skb, struct netlink_callback *cb
static const struct nla_policy vni_filter_entry_policy[VXLAN_VNIFILTER_ENTRY_MAX + 1] = {
[VXLAN_VNIFILTER_ENTRY_START] = { .type = NLA_U32 },
[VXLAN_VNIFILTER_ENTRY_END] = { .type = NLA_U32 },
- [VXLAN_VNIFILTER_ENTRY_GROUP] = { .type = NLA_BINARY,
- .len = sizeof_field(struct iphdr, daddr) },
- [VXLAN_VNIFILTER_ENTRY_GROUP6] = { .type = NLA_BINARY,
- .len = sizeof(struct in6_addr) },
+ [VXLAN_VNIFILTER_ENTRY_GROUP] = NLA_POLICY_EXACT_LEN(sizeof_field(struct iphdr, daddr)),
+ [VXLAN_VNIFILTER_ENTRY_GROUP6] = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
};
static const struct nla_policy vni_filter_policy[VXLAN_VNIFILTER_MAX + 1] = {
--
2.43.0
reply other threads:[~2026-07-04 22:22 UTC|newest]
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