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vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes

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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: f9c4bb0b24 ("vxlan: vni filtering support on collect metadata device")
Reported-by: Weiming Shi <bestswngs@gmail.com>
Signed-off-by: Xiang Mei <xmei5@asu.edu>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260812215341.763123-1-xmei5@asu.edu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Xiang Mei 2026-08-12 14:53:41 -07:00 committed by Jakub Kicinski
parent ba9189c1d0
commit 984f831dda
1 changed files with 2 additions and 4 deletions
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6
drivers/net/vxlan/vxlan_vnifilter.c
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@ -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] = {