Commit 617504c6 authored May 25, 2020 by Horatiu Vultur Committed by David S. Miller May 25, 2020

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: 65369933 ("bridge: mrp: Integrate MRP into the bridge")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 07153961

net/bridge/br_mrp_netlink.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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;

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