From 1c4561d9b5cb25176c85a3aaf4d321c7a20924b2 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 9 Mar 2022 10:29:14 -0800 Subject: [PATCH] net: limit altnames to 64k total [ Upstream commit 155fb43b70b5fce341347a77d1af2765d1e8fbb8 ] Property list (altname is a link "property") is wrapped in a nlattr. nlattrs length is 16bit so practically speaking the list of properties can't be longer than that, otherwise user space would have to interpret broken netlink messages. Prevent the problem from occurring by checking the length of the property list before adding new entries. Reported-by: George Shuklin Reviewed-by: David Ahern Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/rtnetlink.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index a8c319d..9c0e8cc 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3631,12 +3631,23 @@ static int rtnl_alt_ifname(int cmd, struct net_device *dev, struct nlattr *attr, bool *changed, struct netlink_ext_ack *extack) { char *alt_ifname; + size_t size; int err; err = nla_validate(attr, attr->nla_len, IFLA_MAX, ifla_policy, extack); if (err) return err; + if (cmd == RTM_NEWLINKPROP) { + size = rtnl_prop_list_size(dev); + size += nla_total_size(ALTIFNAMSIZ); + if (size >= U16_MAX) { + NL_SET_ERR_MSG(extack, + "effective property list too long"); + return -EINVAL; + } + } + alt_ifname = nla_strdup(attr, GFP_KERNEL_ACCOUNT); if (!alt_ifname) return -ENOMEM; -- 2.7.4