Patch "net: sched: Fix one possible panic when no destroy callback" has been added to the 4.11-stable tree

[<gregkh@linuxfoundation.org>]

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

    net: sched: Fix one possible panic when no destroy callback

to the 4.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-sched-fix-one-possible-panic-when-no-destroy-callback.patch
and it can be found in the queue-4.11 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 Mon Jul 17 18:47:09 CEST 2017
From: Gao Feng <gfree.wind@vip.163.com>
Date: Wed, 28 Jun 2017 12:53:54 +0800
Subject: net: sched: Fix one possible panic when no destroy callback

From: Gao Feng <gfree.wind@vip.163.com>


[ Upstream commit c1a4872ebfb83b1af7144f7b29ac8c4b344a12a8 ]

When qdisc fail to init, qdisc_create would invoke the destroy callback
to cleanup. But there is no check if the callback exists really. So it
would cause the panic if there is no real destroy callback like the qdisc
codel, fq, and so on.

Take codel as an example following:
When a malicious user constructs one invalid netlink msg, it would cause
codel_init->codel_change->nla_parse_nested failed.
Then kernel would invoke the destroy callback directly but qdisc codel
doesn't define one. It causes one panic as a result.

Now add one the check for destroy to avoid the possible panic.

Fixes: 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation")
Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/sch_api.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1008,7 +1008,8 @@ static struct Qdisc *qdisc_create(struct
 		return sch;
 	}
 	/* ops->init() failed, we call ->destroy() like qdisc_create_dflt() */
-	ops->destroy(sch);
+	if (ops->destroy)
+		ops->destroy(sch);
 err_out3:
 	dev_put(dev);
 	kfree((char *) sch - sch->padded);


Patches currently in stable-queue which might be from gfree.wind@vip.163.com are

queue-4.11/net-sched-fix-one-possible-panic-when-no-destroy-callback.patch