From 278b652f0ad9d34158d4834c6b00b95a808fd230 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 77b3d9cc08a1..873081cda950 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3626,12 +3626,23 @@ 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;