From: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
To: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Dmitry Vyukov <dvyukov@google.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
o.rempel@pengutronix.de,
syzbot <syzbot+c3ea30e1e2485573f953@syzkaller.appspotmail.com>,
David Miller <davem@davemloft.net>,
linux-can@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>
Subject: Re: general protection fault in can_rx_register
Date: Tue, 21 Jan 2020 09:30:35 +0100 [thread overview]
Message-ID: <20200121083035.GD14537@x1.vandijck-laurijssen.be> (raw)
In-Reply-To: <2a676c0e-20f2-61b5-c72b-f51947bafc7d@hartkopp.net>
On ma, 20 jan 2020 23:35:16 +0100, Oliver Hartkopp wrote:
> Answering myself ...
>
> On 20/01/2020 23.02, Oliver Hartkopp wrote:
>
> >
> >Added some code to check whether dev->ml_priv is NULL:
> >
> >~/linux$ git diff
> >diff --git a/net/can/af_can.c b/net/can/af_can.c
> >index 128d37a4c2e0..6fb4ae4c359e 100644
> >--- a/net/can/af_can.c
> >+++ b/net/can/af_can.c
> >@@ -463,6 +463,10 @@ int can_rx_register(struct net *net, struct
> >net_device *dev, canid_t can_id,
> > spin_lock_bh(&net->can.rcvlists_lock);
> >
> > dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
> >+ if (!dev_rcv_lists) {
> >+ pr_err("dev_rcv_lists == NULL! %p\n", dev);
> >+ goto out_unlock;
> >+ }
> > rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
> >
> > rcv->can_id = can_id;
> >@@ -479,6 +483,7 @@ int can_rx_register(struct net *net, struct net_device
> >*dev, canid_t can_id,
> > rcv_lists_stats->rcv_entries++;
> > rcv_lists_stats->rcv_entries_max =
> >max(rcv_lists_stats->rcv_entries_max,
> >
> >rcv_lists_stats->rcv_entries);
> >+out_unlock:
> > spin_unlock_bh(&net->can.rcvlists_lock);
> >
> > return err;
> >
> >And the output (after some time) is:
> >
> >[ 758.505841] netlink: 'crash': attribute type 1 has an invalid length.
> >[ 758.508045] bond7148: (slave vxcan1): The slave device specified does
> >not support setting the MAC address
> >[ 758.508057] bond7148: (slave vxcan1): Error -22 calling dev_set_mtu
> >[ 758.532025] bond10413: (slave vxcan1): The slave device specified does
> >not support setting the MAC address
> >[ 758.532043] bond10413: (slave vxcan1): Error -22 calling dev_set_mtu
> >[ 758.532254] dev_rcv_lists == NULL! 000000006b9d257f
> >[ 758.547392] netlink: 'crash': attribute type 1 has an invalid length.
> >[ 758.549310] bond7145: (slave vxcan1): The slave device specified does
> >not support setting the MAC address
> >[ 758.549313] bond7145: (slave vxcan1): Error -22 calling dev_set_mtu
> >[ 758.550464] netlink: 'crash': attribute type 1 has an invalid length.
> >[ 758.552301] bond7146: (slave vxcan1): The slave device specified does
> >not support setting the MAC address
> >
> >So we can see that we get a ml_priv pointer which is NULL which should not
> >be possible due to this:
> >
> >https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/can/dev.c#n743
>
> This reference doesn't point to the right code as vxcan has its own handling
> do assign ml_priv in vxcan.c .
>
> >Btw. the variable 'size' is set two times at the top of alloc_candev_mqs()
> >depending on echo_skb_max. This looks wrong.
>
> No. It looks right as I did not get behind the ALIGN() macro at first sight.
>
> But it is still open why dev->ml_priv is not set correctly in vxcan.c as all
> the settings for .priv_size and in vxcan_setup look fine.
Maybe I got completely lost:
Shouldn't can_ml_priv and vxcan_priv not be similar?
Where is the dev_rcv_lists in the vxcan case?
>
> Best regards,
> Oliver
next prev parent reply other threads:[~2020-01-21 8:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-17 13:46 general protection fault in can_rx_register syzbot
2020-01-17 20:02 ` Oliver Hartkopp
2020-01-20 9:11 ` Kurt Van Dijck
2020-01-20 9:22 ` Dmitry Vyukov
2020-01-20 22:02 ` Oliver Hartkopp
2020-01-20 22:35 ` Oliver Hartkopp
2020-01-21 8:30 ` Kurt Van Dijck [this message]
2020-01-21 8:35 ` Kurt Van Dijck
2020-01-21 18:54 ` Kurt Van Dijck
2020-01-21 19:28 ` Oliver Hartkopp
2020-01-21 19:47 ` Kurt Van Dijck
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