Patchwork net: add checks if dev->netdev_ops is NULL in register_netdevice()

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Submitter dingtianhong
Date April 8, 2013, 9:43 a.m.
Message ID <51629159.9040000@huawei.com>
Download mbox | patch
Permalink /patch/234619/
State Rejected
Delegated to: David Miller
Headers show

Comments

dingtianhong - April 8, 2013, 9:43 a.m.
In some cases netdev->netdev_ops could be NULL in the register_netdevice(),
thus a NULL point deference happens and lead to oops:

[ 8260.836400] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 8260.955306] IP: [<ffffffff81388333>] register_netdevice+0x73/0x2d0
[ 8261.054888] PGD 2f4dcd067 PUD 2f4de0067 PMD 0
[ 8261.134244] Oops: 0000 [#1] SMP
[ 8261.198938] CPU 0
[ 8262.605182] RIP: 0010:[<ffffffff81388333>]  [<ffffffff81388333>] register_netdevice+0x73/0x2d0
[ 8262.741859] RSP: 0018:ffff8802f489f9f8  EFLAGS: 00010246
[ 8262.839463] RAX: 0000000000000000 RBX: ffff8802f4e73000 RCX: ffff8802f4e73006
[ 8262.959484] RDX: 0000000000000000 RSI: 00000000daa92527 RDI: ffff8802f4e73006
[ 8263.079352] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff880327d898c0
[ 8263.198987] R10: 00000000000000c1 R11: 0000000000000000 R12: ffffffff81fed080
[ 8263.318401] R13: ffffffff81fed080 R14: ffff8802f4e73000 R15: 0000000000000000
[ 8263.438014] FS:  00007f01dfa81700(0000) GS:ffff88033f200000(0000) knlGS:0000000000000000
[ 8263.569778] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8263.673859] CR2: 0000000000000000 CR3: 000000032893f000 CR4: 00000000000006f0
[ 8263.794922] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 8263.915734] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 8264.036251] Process rmcli (pid: 14089, threadinfo ffff8802f489e000, task ffff880324708080)
[ 8264.170961] Stack:
[ 8264.231328]  ffff88032a3c0000 0000000000000003 0000000000000003 ffff88032a3c0000
[ 8264.356967]  0000000000000003 ffffffffa039dbcb 000000003ec216c0 0000000000000246
[ 8264.483081]  382e30363238205b 00205d3900000006 ff00305f63696e76 0000000000000003

We should check the point to avoid the oops.

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 1.8.0

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Eric Dumazet - April 8, 2013, 3:16 p.m.
On Mon, 2013-04-08 at 17:43 +0800, dingtianhong wrote:
> In some cases netdev->netdev_ops could be NULL in the register_netdevice(),
> thus a NULL point deference happens and lead to oops:

>  	/* Init, if this function is available */
> -	if (dev->netdev_ops->ndo_init) {
> +	if (dev->netdev_ops && dev->netdev_ops->ndo_init) {
>  		ret = dev->netdev_ops->ndo_init(dev);
>  		if (ret) {
>  			if (ret > 0)
> -- 1.8.0
> 

Seriously ?

This patch is not needed, and not complete anyway.

Fix the driver instead, we don't want this to happen.



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David Miller - April 8, 2013, 3:34 p.m.
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 08 Apr 2013 08:16:34 -0700

> On Mon, 2013-04-08 at 17:43 +0800, dingtianhong wrote:
>> In some cases netdev->netdev_ops could be NULL in the register_netdevice(),
>> thus a NULL point deference happens and lead to oops:
> 
>>  	/* Init, if this function is available */
>> -	if (dev->netdev_ops->ndo_init) {
>> +	if (dev->netdev_ops && dev->netdev_ops->ndo_init) {
>>  		ret = dev->netdev_ops->ndo_init(dev);
>>  		if (ret) {
>>  			if (ret > 0)
>> -- 1.8.0
>> 
> 
> Seriously ?
> 
> This patch is not needed, and not complete anyway.
> 
> Fix the driver instead, we don't want this to happen.

Agreed, I'm not seriously considering patches like this at all.
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Alexander Duyck - April 8, 2013, 3:49 p.m.
On 04/08/2013 02:43 AM, dingtianhong wrote:
> In some cases netdev->netdev_ops could be NULL in the register_netdevice(),
> thus a NULL point deference happens and lead to oops:
>
> [ 8260.836400] BUG: unable to handle kernel NULL pointer dereference at (null)
> [ 8260.955306] IP: [<ffffffff81388333>] register_netdevice+0x73/0x2d0
> [ 8261.054888] PGD 2f4dcd067 PUD 2f4de0067 PMD 0
> [ 8261.134244] Oops: 0000 [#1] SMP
> [ 8261.198938] CPU 0
> [ 8262.605182] RIP: 0010:[<ffffffff81388333>]  [<ffffffff81388333>] register_netdevice+0x73/0x2d0
> [ 8262.741859] RSP: 0018:ffff8802f489f9f8  EFLAGS: 00010246
> [ 8262.839463] RAX: 0000000000000000 RBX: ffff8802f4e73000 RCX: ffff8802f4e73006
> [ 8262.959484] RDX: 0000000000000000 RSI: 00000000daa92527 RDI: ffff8802f4e73006
> [ 8263.079352] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff880327d898c0
> [ 8263.198987] R10: 00000000000000c1 R11: 0000000000000000 R12: ffffffff81fed080
> [ 8263.318401] R13: ffffffff81fed080 R14: ffff8802f4e73000 R15: 0000000000000000
> [ 8263.438014] FS:  00007f01dfa81700(0000) GS:ffff88033f200000(0000) knlGS:0000000000000000
> [ 8263.569778] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 8263.673859] CR2: 0000000000000000 CR3: 000000032893f000 CR4: 00000000000006f0
> [ 8263.794922] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 8263.915734] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 8264.036251] Process rmcli (pid: 14089, threadinfo ffff8802f489e000, task ffff880324708080)
> [ 8264.170961] Stack:
> [ 8264.231328]  ffff88032a3c0000 0000000000000003 0000000000000003 ffff88032a3c0000
> [ 8264.356967]  0000000000000003 ffffffffa039dbcb 000000003ec216c0 0000000000000246
> [ 8264.483081]  382e30363238205b 00205d3900000006 ff00305f63696e76 0000000000000003
>
> We should check the point to avoid the oops.
>
> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> ---
>  net/core/dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index e7d68ed..596a11e 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5159,7 +5159,7 @@ int register_netdevice(struct net_device *dev)
>  		goto out;
>
>  	/* Init, if this function is available */
> -	if (dev->netdev_ops->ndo_init) {
> +	if (dev->netdev_ops && dev->netdev_ops->ndo_init) {
>  		ret = dev->netdev_ops->ndo_init(dev);
>  		if (ret) {
>  			if (ret > 0)
> -- 1.8.0
>

The correct fix for this is to not allow the registration of devices
with a null netdev_ops pointer.  The subtle approach to resolving this
is adding a check for the null pointer near the start of the function
and returning -EVINAL since the dev structure passed was configured
incorrectly.  The blunt approach is to just add a BUG_ON with a comment
on the line before it explaining that you should always set the
netdev_ops pointer before trying to register a netdev.  That way if
someone else makes the mistake then they will hit the BUG_ON and realize
what they are doing wrong.

Thanks,

Alex
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stephen hemminger - April 10, 2013, 8:45 p.m.
On Mon, 8 Apr 2013 17:43:53 +0800
dingtianhong <dingtianhong@huawei.com> wrote:

> In some cases netdev->netdev_ops could be NULL in the register_netdevice(),
> thus a NULL point deference happens and lead to oops:
> 
> [ 8260.836400] BUG: unable to handle kernel NULL pointer dereference at (null)
> [ 8260.955306] IP: [<ffffffff81388333>] register_netdevice+0x73/0x2d0
> [ 8261.054888] PGD 2f4dcd067 PUD 2f4de0067 PMD 0
> [ 8261.134244] Oops: 0000 [#1] SMP
> [ 8261.198938] CPU 0
> [ 8262.605182] RIP: 0010:[<ffffffff81388333>]  [<ffffffff81388333>] register_netdevice+0x73/0x2d0
> [ 8262.741859] RSP: 0018:ffff8802f489f9f8  EFLAGS: 00010246
> [ 8262.839463] RAX: 0000000000000000 RBX: ffff8802f4e73000 RCX: ffff8802f4e73006
> [ 8262.959484] RDX: 0000000000000000 RSI: 00000000daa92527 RDI: ffff8802f4e73006
> [ 8263.079352] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff880327d898c0
> [ 8263.198987] R10: 00000000000000c1 R11: 0000000000000000 R12: ffffffff81fed080
> [ 8263.318401] R13: ffffffff81fed080 R14: ffff8802f4e73000 R15: 0000000000000000
> [ 8263.438014] FS:  00007f01dfa81700(0000) GS:ffff88033f200000(0000) knlGS:0000000000000000
> [ 8263.569778] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 8263.673859] CR2: 0000000000000000 CR3: 000000032893f000 CR4: 00000000000006f0
> [ 8263.794922] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 8263.915734] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 8264.036251] Process rmcli (pid: 14089, threadinfo ffff8802f489e000, task ffff880324708080)
> [ 8264.170961] Stack:
> [ 8264.231328]  ffff88032a3c0000 0000000000000003 0000000000000003 ffff88032a3c0000
> [ 8264.356967]  0000000000000003 ffffffffa039dbcb 000000003ec216c0 0000000000000246
> [ 8264.483081]  382e30363238205b 00205d3900000006 ff00305f63696e76 0000000000000003
> 
> We should check the point to avoid the oops.
> 
> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>

I notice you truncated the back trace. You should include the whole thing
so the buggy driver can be found and shot. If it is your own code fix it.

Adding a BUG_ON() is a waste, the NULL trap is the same effect.

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Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index e7d68ed..596a11e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5159,7 +5159,7 @@  int register_netdevice(struct net_device *dev)
 		goto out;

 	/* Init, if this function is available */
-	if (dev->netdev_ops->ndo_init) {
+	if (dev->netdev_ops && dev->netdev_ops->ndo_init) {
 		ret = dev->netdev_ops->ndo_init(dev);
 		if (ret) {
 			if (ret > 0)