[PATCH 6.1 029/127] rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length

Greg Kroah-Hartman
2023-08-09T10:52:34Z

From: Lin Ma <linma@zju.edu.cn>

[ Upstream commit d73ef2d69c0dba5f5a1cb9600045c873bab1fb7f ]

There are totally 9 ndo_bridge_setlink handlers in the current kernel,
which are 1) bnxt_bridge_setlink, 2) be_ndo_bridge_setlink 3)
i40e_ndo_bridge_setlink 4) ice_bridge_setlink 5)
ixgbe_ndo_bridge_setlink 6) mlx5e_bridge_setlink 7)
nfp_net_bridge_setlink 8) qeth_l2_bridge_setlink 9) br_setlink.

By investigating the code, we find that 1-7 parse and use nlattr
IFLA_BRIDGE_MODE but 3 and 4 forget to do the nla_len check. This can
lead to an out-of-attribute read and allow a malformed nlattr (e.g.,
length 0) to be viewed as a 2 byte integer.

To avoid such issues, also for other ndo_bridge_setlink handlers in the
future. This patch adds the nla_len check in rtnl_bridge_setlink and
does an early error return if length mismatches. To make it works, the
break is removed from the parsing for IFLA_BRIDGE_FLAGS to make sure
this nla_for_each_nested iterates every attribute.

Fixes: b1edc14a3fbf ("ice: Implement ice_bridge_getlink and ice_bridge_setlink")
Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20230726075314.1059224-1-linma@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/rtnetlink.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 5625ed30a06f3..2758b3f7c0214 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -5030,13 +5030,17 @@ static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
if (br_spec) {
nla_for_each_nested(attr, br_spec, rem) {
- if (nla_type(attr) == IFLA_BRIDGE_FLAGS) {
+ if (nla_type(attr) == IFLA_BRIDGE_FLAGS && !have_flags) {
if (nla_len(attr) < sizeof(flags))
return -EINVAL;

have_flags = true;
flags = nla_get_u16(attr);
- break;
+ }
+
+ if (nla_type(attr) == IFLA_BRIDGE_MODE) {
+ if (nla_len(attr) < sizeof(u16))
+ return -EINVAL;
}
}
}
--
2.40.1