Patch "rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length

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:
     rtnetlink-let-rtnl_bridge_setlink-checks-ifla_bridge.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.



commit 532dc16e51b73b9784dcc70e041a29a501b53626
Author: Lin Ma <linma@xxxxxxxxxx>
Date:   Wed Jul 26 15:53:14 2023 +0800

    rtnetlink: let rtnl_bridge_setlink checks IFLA_BRIDGE_MODE length
    
    [ Upstream commit d73ef2d69c0dba5f5a1cb9600045c873bab1fb7f ]
    
    There are totally 9 ndo_bridge_setlink handlers in the current kernel,
    which are 1) bnxt_bridge_setlink, 2) be_ndo_bridge_setlink 3)
    i40e_ndo_bridge_setlink 4) ice_bridge_setlink 5)
    ixgbe_ndo_bridge_setlink 6) mlx5e_bridge_setlink 7)
    nfp_net_bridge_setlink 8) qeth_l2_bridge_setlink 9) br_setlink.
    
    By investigating the code, we find that 1-7 parse and use nlattr
    IFLA_BRIDGE_MODE but 3 and 4 forget to do the nla_len check. This can
    lead to an out-of-attribute read and allow a malformed nlattr (e.g.,
    length 0) to be viewed as a 2 byte integer.
    
    To avoid such issues, also for other ndo_bridge_setlink handlers in the
    future. This patch adds the nla_len check in rtnl_bridge_setlink and
    does an early error return if length mismatches. To make it works, the
    break is removed from the parsing for IFLA_BRIDGE_FLAGS to make sure
    this nla_for_each_nested iterates every attribute.
    
    Fixes: b1edc14a3fbf ("ice: Implement ice_bridge_getlink and ice_bridge_setlink")
    Fixes: 51616018dd1b ("i40e: Add support for getlink, setlink ndo ops")
    Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
    Acked-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
    Reviewed-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
    Link: https://lore.kernel.org/r/20230726075314.1059224-1-linma@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d3c03ebf06a5b..ce37a052b9c32 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -4897,13 +4897,17 @@ static int rtnl_bridge_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	br_spec = nlmsg_find_attr(nlh, sizeof(struct ifinfomsg), IFLA_AF_SPEC);
 	if (br_spec) {
 		nla_for_each_nested(attr, br_spec, rem) {
-			if (nla_type(attr) == IFLA_BRIDGE_FLAGS) {
+			if (nla_type(attr) == IFLA_BRIDGE_FLAGS && !have_flags) {
 				if (nla_len(attr) < sizeof(flags))
 					return -EINVAL;
 
 				have_flags = true;
 				flags = nla_get_u16(attr);
-				break;
+			}
+
+			if (nla_type(attr) == IFLA_BRIDGE_MODE) {
+				if (nla_len(attr) < sizeof(u16))
+					return -EINVAL;
 			}
 		}
 	}