linux-kernel - [PATCH 5.15 21/72] ipv4: Check attribute length for RTA

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Date:   Mon, 10 Jan 2022 08:22:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.15 21/72] ipv4: Check attribute length for RTA_FLOW in multipath route

From: David Ahern <dsahern@...nel.org>

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@...nel.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -731,8 +731,13 @@ 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);
@@ -963,8 +968,14 @@ 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
 		}