This is a note to let you know that I've just added the patch titled ipv6: Check attribute length for RTA_GATEWAY in multipath route to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ipv6-check-attribute-length-for-rta_gateway-in-multipath-route.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 4619bcf91399f00a40885100fb61d594d8454033 Mon Sep 17 00:00:00 2001 From: David Ahern <dsahern@xxxxxxxxxx> Date: Thu, 30 Dec 2021 17:36:33 -0700 Subject: ipv6: Check attribute length for RTA_GATEWAY in multipath route From: David Ahern <dsahern@xxxxxxxxxx> commit 4619bcf91399f00a40885100fb61d594d8454033 upstream. Commit referenced in the Fixes tag used nla_memcpy for RTA_GATEWAY as does the current nla_get_in6_addr. nla_memcpy protects against accessing memory greater than what is in the attribute, but there is no check requiring the attribute to have an IPv6 address. Add it. Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)") Signed-off-by: David Ahern <dsahern@xxxxxxxxxx> Cc: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/route.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -5113,6 +5113,19 @@ out: return should_notify; } +static int fib6_gw_from_attr(struct in6_addr *gw, struct nlattr *nla, + struct netlink_ext_ack *extack) +{ + if (nla_len(nla) < sizeof(*gw)) { + NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_GATEWAY"); + return -EINVAL; + } + + *gw = nla_get_in6_addr(nla); + + return 0; +} + static int ip6_route_multipath_add(struct fib6_config *cfg, struct netlink_ext_ack *extack) { @@ -5153,7 +5166,13 @@ static int ip6_route_multipath_add(struc nla = nla_find(attrs, attrlen, RTA_GATEWAY); if (nla) { - r_cfg.fc_gateway = nla_get_in6_addr(nla); + int ret; + + ret = fib6_gw_from_attr(&r_cfg.fc_gateway, nla, + extack); + if (ret) + return ret; + r_cfg.fc_flags |= RTF_GATEWAY; } r_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP); Patches currently in stable-queue which might be from dsahern@xxxxxxxxxx are queue-5.10/ipv4-check-attribute-length-for-rta_flow-in-multipath-route.patch queue-5.10/ipv6-check-attribute-length-for-rta_gateway-when-deleting-multipath-route.patch queue-5.10/ipv6-check-attribute-length-for-rta_gateway-in-multipath-route.patch queue-5.10/lwtunnel-validate-rta_encap_type-attribute-length.patch queue-5.10/ipv4-check-attribute-length-for-rta_gateway-in-multipath-route.patch