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

bridge: check brport attr show in brport_show

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: bridge-check-brport-attr-show-in-brport_show.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Tue Mar 6 19:02:12 PST 2018

From: Xin Long lucien.xin@gmail.com Date: Mon, 12 Feb 2018 17:15:40 +0800 Subject: bridge: check brport attr show in brport_show

From: Xin Long lucien.xin@gmail.com

[ Upstream commit 1b12580af1d0677c3c3a19e35bfe5d59b03f737f ]

Now br_sysfs_if file flush doesn't have attr show. To read it will cause kernel panic after users chmod u+r this file.

Xiong found this issue when running the commands:

ip link add br0 type bridge ip link add type veth ip link set veth0 master br0 chmod u+r /sys/devices/virtual/net/veth0/brport/flush timeout 3 cat /sys/devices/virtual/net/veth0/brport/flush

kernel crashed with NULL a pointer dereference call trace.

This patch is to fix it by return -EINVAL when brport_attr->show is null, just the same as the check for brport_attr->store in brport_store().

Fixes: 9cf637473c85 ("bridge: add sysfs hook to flush forwarding table") Reported-by: Xiong Zhou xzhou@redhat.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bridge/br_sysfs_if.c | 3 +++ 1 file changed, 3 insertions(+)

--- a/net/bridge/br_sysfs_if.c +++ b/net/bridge/br_sysfs_if.c @@ -235,6 +235,9 @@ static ssize_t brport_show(struct kobjec struct brport_attribute *brport_attr = to_brport_attr(attr); struct net_bridge_port *p = to_brport(kobj);

+ if (!brport_attr->show) + return -EINVAL; + return brport_attr->show(p, buf); }

Patches currently in stable-queue which might be from lucien.xin@gmail.com are

queue-4.14/bridge-check-brport-attr-show-in-brport_show.patch queue-4.14/sctp-do-not-pr_err-for-the-duplicated-node-in-transport-rhlist.patch