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bridge: mrp: Fix out-of-bounds read in br_mrp_parse

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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: 6536993371 ("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>
This commit is contained in:
Horatiu Vultur 2020-05-25 09:55:41 +00:00 committed by David S. Miller
parent 07153961f8
commit 617504c67e
1 changed files with 6 additions and 0 deletions
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6
net/bridge/br_mrp_netlink.c
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@ -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;