Commit fd63f185 authored by Paolo Abeni's avatar Paolo Abeni Committed by Jakub Kicinski
Browse files

ipv6: prevent possible UaF in addrconf_permanent_addr() 



The mentioned helper try to warn the user about an exceptional
condition, but the message is delivered too late, accessing the ipv6
after its possible deletion.

Reorder the statement to avoid the possible UaF; while at it, place the
warning outside the idev->lock as it needs no protection.

Reported-by: default avatarJakub Kicinski <kuba@kernel.org>
Closes: https://sashiko.dev/#/patchset/8c8bfe2e1a324e501f0e15fef404a77443fd8caf.1774365668.git.pabeni%40redhat.com


Fixes: f1705ec1 ("net: ipv6: Make address flushing on ifdown optional")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Link: https://patch.msgid.link/ef973c3a8cb4f8f1787ed469f3e5391b9fe95aa0.1774601542.git.pabeni@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent dc9e9d61

net/ipv6/addrconf.c

+3 −3
Original line number Diff line number Diff line
@@ -3625,12 +3625,12 @@ static void addrconf_permanent_addr(struct net *net, struct net_device *dev) 
		if ((ifp->flags & IFA_F_PERMANENT) &&

		    fixup_permanent_addr(net, idev, ifp) < 0) {

			write_unlock_bh(&idev->lock);

			in6_ifa_hold(ifp);

			ipv6_del_addr(ifp);

			write_lock_bh(&idev->lock);



			net_info_ratelimited("%s: Failed to add prefix route for address %pI6c; dropping\n",

					     idev->dev->name, &ifp->addr);

			in6_ifa_hold(ifp);

			ipv6_del_addr(ifp);

			write_lock_bh(&idev->lock);

		}

	}