[PATCH 5.10 18/43] ipv4: Check attribute length for RTA_FLOW in multipath route

From: Greg Kroah-Hartman
Date: Mon Jan 10 2022 - 02:37:47 EST


From: David Ahern <dsahern@xxxxxxxxxx>

commit 664b9c4b7392ce723b013201843264bf95481ce5 upstream.

Make sure RTA_FLOW is at least 4B before using.

Fixes: 4e902c57417c ("[IPv4]: FIB configuration using struct fib_config")
Signed-off-by: David Ahern <dsahern@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/fib_semantics.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -732,8 +732,13 @@ static int fib_get_nhs(struct fib_info *
}

nla = nla_find(attrs, attrlen, RTA_FLOW);
- if (nla)
+ if (nla) {
+ if (nla_len(nla) < sizeof(u32)) {
+ NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+ return -EINVAL;
+ }
fib_cfg.fc_flow = nla_get_u32(nla);
+ }

fib_cfg.fc_encap = nla_find(attrs, attrlen, RTA_ENCAP);
nla = nla_find(attrs, attrlen, RTA_ENCAP_TYPE);
@@ -964,8 +969,14 @@ int fib_nh_match(struct net *net, struct

#ifdef CONFIG_IP_ROUTE_CLASSID
nla = nla_find(attrs, attrlen, RTA_FLOW);
- if (nla && nla_get_u32(nla) != nh->nh_tclassid)
- return 1;
+ if (nla) {
+ if (nla_len(nla) < sizeof(u32)) {
+ NL_SET_ERR_MSG(extack, "Invalid RTA_FLOW");
+ return -EINVAL;
+ }
+ if (nla_get_u32(nla) != nh->nh_tclassid)
+ return 1;
+ }
#endif
}