From 617504c67e01d30310558442777a4112ea6d587d Mon Sep 17 00:00:00 2001 From: Horatiu Vultur Date: Mon, 25 May 2020 09:55:41 +0000 Subject: [PATCH] bridge: mrp: Fix out-of-bounds read in br_mrp_parse The issue was reported by syzbot. When the function br_mrp_parse was called with a valid net_bridge_port, the net_bridge was an invalid pointer. Therefore the check br->stp_enabled could pass/fail depending where it was pointing in memory. The fix consists of setting the net_bridge pointer if the port is a valid pointer. Reported-by: syzbot+9c6f0f1f8e32223df9a4@syzkaller.appspotmail.com Fixes: 6536993371fa ("bridge: mrp: Integrate MRP into the bridge") Signed-off-by: Horatiu Vultur Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller --- net/bridge/br_mrp_netlink.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/bridge/br_mrp_netlink.c b/net/bridge/br_mrp_netlink.c index 397e7f710772..4a08a99519b0 100644 --- a/net/bridge/br_mrp_netlink.c +++ b/net/bridge/br_mrp_netlink.c @@ -27,6 +27,12 @@ int br_mrp_parse(struct net_bridge *br, struct net_bridge_port *p, struct nlattr *tb[IFLA_BRIDGE_MRP_MAX + 1]; int err; + /* When this function is called for a port then the br pointer is + * invalid, therefor set the br to point correctly + */ + if (p) + br = p->br; + if (br->stp_enabled != BR_NO_STP) { NL_SET_ERR_MSG_MOD(extack, "MRP can't be enabled if STP is already enabled"); return -EINVAL; -- 2.11.0