Date:	Tue, 19 Apr 2016 18:44:41 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	"David Rivshin (Allworx)" <drivshin.allworx@...il.com>
CC:	Andrew Goodbody <andrew.goodbody@...brionix.com>,
	<netdev@...r.kernel.org>, "David S. Miller" <davem@...emloft.net>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<mugunthanvnm@...com>, <tony@...mide.com>
Subject: Re: [PATCH v2 1/1] drivers: net: cpsw: Prevent NUll pointer
 dereference with two PHYs

On 04/19/2016 06:01 PM, David Rivshin (Allworx) wrote:
> On Tue, 19 Apr 2016 17:41:07 +0300
> Grygorii Strashko <grygorii.strashko@...com> wrote:
> 
>> Hi,
>>
>> On 04/19/2016 04:56 PM, Andrew Goodbody wrote:
>>> Adding a 2nd PHY to cpsw results in a NULL pointer dereference
>>> as below. Fix by maintaining a reference to each PHY node in slave
>>> struct instead of a single reference in the priv struct which was
>>> overwritten by the 2nd PHY.
>>
>> David, Is it possible to drop prev version of this patch from linux-next
>> - it breaks boot on many TI boards with -next.
>>
>>
>>>
>>> [   17.870933] Unable to handle kernel NULL pointer dereference at virtual address 00000180
>>> [   17.879557] pgd = dc8bc000
>>> [   17.882514] [00000180] *pgd=9c882831, *pte=00000000, *ppte=00000000
>>> [   17.889213] Internal error: Oops: 17 [#1] ARM
>>> [   17.893838] Modules linked in:
>>> [   17.897102] CPU: 0 PID: 1657 Comm: connmand Not tainted 4.5.0-ge463dfb-dirty #11
>>> [   17.904947] Hardware name: Cambrionix whippet
>>> [   17.909576] task: dc859240 ti: dc968000 task.ti: dc968000
>>> [   17.915339] PC is at phy_attached_print+0x18/0x8c
>>> [   17.920339] LR is at phy_attached_info+0x14/0x18
>>> [   17.925247] pc : [<c042baec>]    lr : [<c042bb74>]    psr: 600f0113
>>> [   17.925247] sp : dc969cf8  ip : dc969d28  fp : dc969d18
>>> [   17.937425] r10: dda7a400  r9 : 00000000  r8 : 00000000
>>> [   17.942971] r7 : 00000001  r6 : ddb00480  r5 : ddb8cb34  r4 : 00000000
>>> [   17.949898] r3 : c0954cc0  r2 : c09562b0  r1 : 00000000  r0 : 00000000
>>> [   17.956829] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
>>> [   17.964401] Control: 10c5387d  Table: 9c8bc019  DAC: 00000051
>>> [   17.970500] Process connmand (pid: 1657, stack limit = 0xdc968210)
>>> [   17.977059] Stack: (0xdc969cf8 to 0xdc96a000)
>>
>> [...]
>>
>>> [   18.323956] [<c05e4cb8>] (inet_ioctl) from [<c055f5ac>] (sock_ioctl+0x15c/0x2d8)
>>> [   18.331829] [<c055f450>] (sock_ioctl) from [<c010b388>] (do_vfs_ioctl+0x98/0x8d0)
>>> [   18.339765]  r7:00008914 r6:dc8ab4c0 r5:dd257ae0 r4:beaeda20
>>> [   18.345822] [<c010b2f0>] (do_vfs_ioctl) from [<c010bc34>] (SyS_ioctl+0x74/0x84)
>>> [   18.353573]  r10:00000000 r9:00000011 r8:beaeda20 r7:00008914 r6:dc8ab4c0 r5:dc8ab4c0
>>> [   18.361924]  r4:00000000
>>> [   18.364653] [<c010bbc0>] (SyS_ioctl) from [<c00163e0>] (ret_fast_syscall+0x0/0x3c)
>>> [   18.372682]  r9:dc968000 r8:c00165e8 r7:00000036 r6:00000002 r5:00000011 r4:00000000
>>> [   18.380960] Code: e92dd810 e24cb010 e24dd010 e59b4004 (e5902180)
>>> [   18.387580] ---[ end trace c80529466223f3f3 ]---
>>
>> ^ Could you make it shorter and drop timestamps, pls?
>>
>>>
>>> Signed-off-by: Andrew Goodbody <andrew.goodbody@...brionix.com>
>>> ---
>>>
>>> v2 - Move allocation of memory for priv->slaves to inside cpsw_probe_dt so it
>>>        has data->slaves initialised first which is needed to calculate size
>>>
>>>    drivers/net/ethernet/ti/cpsw.c | 30 +++++++++++++++---------------
>>>    1 file changed, 15 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
>>> index 42fdfd4..e62909c 100644
>>> --- a/drivers/net/ethernet/ti/cpsw.c
>>> +++ b/drivers/net/ethernet/ti/cpsw.c
>>> @@ -349,6 +349,7 @@ struct cpsw_slave {
>>>    	struct cpsw_slave_data		*data;
>>>    	struct phy_device		*phy;
>>>    	struct net_device		*ndev;
>>> +	struct device_node		*phy_node;
>>>    	u32				port_vlan;
>>>    	u32				open_stat;
>>>    };
>>> @@ -367,7 +368,6 @@ struct cpsw_priv {
>>>    	spinlock_t			lock;
>>>    	struct platform_device		*pdev;
>>>    	struct net_device		*ndev;
>>> -	struct device_node		*phy_node;
>>>    	struct napi_struct		napi_rx;
>>>    	struct napi_struct		napi_tx;
>>>    	struct device			*dev;
>>> @@ -1148,8 +1148,8 @@ static void cpsw_slave_open(struct cpsw_slave *slave, struct cpsw_priv *priv)
>>>    		cpsw_ale_add_mcast(priv->ale, priv->ndev->broadcast,
>>>    				   1 << slave_port, 0, 0, ALE_MCAST_FWD_2);
>>>    
>>> -	if (priv->phy_node)
>>> -		slave->phy = of_phy_connect(priv->ndev, priv->phy_node,
>>> +	if (slave->phy_node)
>>> +		slave->phy = of_phy_connect(priv->ndev, slave->phy_node,
>>>    				 &cpsw_adjust_link, 0, slave->data->phy_if);
>>>    	else
>>>    		slave->phy = phy_connect(priv->ndev, slave->data->phy_id,
>>> @@ -1946,7 +1946,7 @@ static int cpsw_probe_dt(struct cpsw_priv *priv,
>>>    	struct device_node *node = pdev->dev.of_node;
>>>    	struct device_node *slave_node;
>>>    	struct cpsw_platform_data *data = &priv->data;
>>> -	int i = 0, ret;
>>> +	int i, ret;
>>>    	u32 prop;
>>>    
>>>    	if (!node)
>>> @@ -1958,6 +1958,14 @@ static int cpsw_probe_dt(struct cpsw_priv *priv,
>>>    	}
>>>    	data->slaves = prop;
>>>    
>>> +	priv->slaves = devm_kzalloc(&pdev->dev,
>>> +				    sizeof(struct cpsw_slave) * data->slaves,
>>> +				    GFP_KERNEL);
>>> +	if (!priv->slaves)
>>> +		return -ENOMEM;
>>> +	for (i = 0; i < data->slaves; i++)
>>> +		priv->slaves[i].slave_num = i;
>>> +
>>>    	if (of_property_read_u32(node, "active_slave", &prop)) {
>>>    		dev_err(&pdev->dev, "Missing active_slave property in the DT.\n");
>>>    		return -EINVAL;
>>> @@ -2023,6 +2031,7 @@ static int cpsw_probe_dt(struct cpsw_priv *priv,
>>>    	if (ret)
>>>    		dev_warn(&pdev->dev, "Doesn't have any child node\n");
>>>    
>>> +	i = 0;
>>>    	for_each_child_of_node(node, slave_node) {
>>>    		struct cpsw_slave_data *slave_data = data->slave_data + i;
>>>    		const void *mac_addr = NULL;
>>> @@ -2033,7 +2042,8 @@ static int cpsw_probe_dt(struct cpsw_priv *priv,
>>>    		if (strcmp(slave_node->name, "slave"))
>>>    			continue;
>>>    
>>> -		priv->phy_node = of_parse_phandle(slave_node, "phy-handle", 0);
>>> +		priv->slaves[i].phy_node =
>>> +			of_parse_phandle(slave_node, "phy-handle", 0);
>>
>> i++?
>>
>> Ideally, the simplest way is to save phy_node in slave_data, but ...
>> (see comment below).
> 
> FYI, I have a patch [1] that does exactly that in my queue. Sorry
> I've been busy and haven't had a chance to rebase/retest/resubmit
> since Nicolas gave his Tested-By (and I missed Andrew's original
> patch). I can probably steal some time to resurrect that quickly
> if it's preferred, just let me know.
> 
> [1] http://www.spinics.net/lists/netdev/msg357772.html

Ah Ok. There are no user of cpsw_platform_data outside of net/ethernet/ti/,
so yes, looks like your patch 1 does exactly what's needed.

> 
>>
>>
>>>    		parp = of_get_property(slave_node, "phy_id", &lenp);
>>>    		if (of_phy_is_fixed_link(slave_node)) {
>>>    			struct device_node *phy_node;
>>> @@ -2292,16 +2302,6 @@ static int cpsw_probe(struct platform_device *pdev)
>>>    
>>>    	memcpy(ndev->dev_addr, priv->mac_addr, ETH_ALEN);
>>>    
>>> -	priv->slaves = devm_kzalloc(&pdev->dev,
>>> -				    sizeof(struct cpsw_slave) * data->slaves,
>>> -				    GFP_KERNEL);
>>> -	if (!priv->slaves) {
>>> -		ret = -ENOMEM;
>>> -		goto clean_runtime_disable_ret;
>>> -	}
>> I don't think you can move this out from here - it will break legacy boot :(
>>
>>
>>> -	for (i = 0; i < data->slaves; i++)
>>> -		priv->slaves[i].slave_num = i;
>>
>> Personally, I see only one safe way to do it without big rework -
>> do second pass of DT parsing here to fill phy_node field.
>>
 


-- 
regards,
-grygorii

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