linux-kernel - Re: [PATCH] infiniband: hw: cxgb3: cxio_hal.c: Cleaning up missing null-terminate after strncpy call

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Date:	Mon, 18 Aug 2014 18:25:36 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Steve Wise <swise@...ngridcomputing.com>
Cc:	Steve Wise <swise@...lsio.com>, Roland Dreier <roland@...nel.org>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal.rosenstock@...il.com>,
	linux-rdma@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] infiniband: hw: cxgb3: cxio_hal.c: Cleaning up missing
 null-terminate after strncpy call

2014-08-18 16:27 GMT+02:00 Steve Wise <swise@...ngridcomputing.com>:
>
>
>> -----Original Message-----
>> From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-owner@...r.kernel.org]
>> On Behalf Of Rickard Strandqvist
>> Sent: Sunday, August 17, 2014 5:40 PM
>> To: Steve Wise; Roland Dreier
>> Cc: Rickard Strandqvist; Sean Hefty; Hal Rosenstock; linux-rdma@...r.kernel.org; linux-
>> kernel@...r.kernel.org
>> Subject: [PATCH] infiniband: hw: cxgb3: cxio_hal.c: Cleaning up missing null-terminate
> after
>> strncpy call
>>
>> Added a guaranteed null-terminate after call to strncpy.
>>
>> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
>> ---
>>  drivers/infiniband/hw/cxgb3/cxio_hal.c |    1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/infiniband/hw/cxgb3/cxio_hal.c
>> b/drivers/infiniband/hw/cxgb3/cxio_hal.c
>> index de1c61b4..5fc04e4 100644
>> --- a/drivers/infiniband/hw/cxgb3/cxio_hal.c
>> +++ b/drivers/infiniband/hw/cxgb3/cxio_hal.c
>> @@ -933,6 +933,7 @@ int cxio_rdev_open(struct cxio_rdev *rdev_p)
>>               netdev_p = rdev_p->t3cdev_p->lldev;
>>               strncpy(rdev_p->dev_name, rdev_p->t3cdev_p->name,
>>                       T3_MAX_DEV_NAME_LEN);
>> +             rdev_p->dev_name[T3_MAX_DEV_NAME_LEN - 1] = '\0';
>>       } else {
>>               PDBG("%s t3cdev_p or dev_name must be set\n", __func__);
>>               return -EINVAL;
>
> cxio_rdev_open() is called only by open_rnic_dev() which allocates the device structure by
> calling ib_alloc_device() which uses kzalloc().  So this change really isn't needed, is
> it?
>
> Steve.
>



Hi

Sure, strlcpy is preferable in many ways if we only can guarantee that
it is safe.
I have seldom received so much criticism when I start switching to
strlcpy, although much of it was justified :)
Even Linus was getting into the debate.  See more:

https://plus.google.com/111049168280159033135/posts/1amLbuhWbh5


I change to strlcpy only when I'm sure it will not cause any other problems.
But if you or anyone else can guarantee that in this case, so I'd make
a new patch with strlcpy.

And no Steve, or then you have to use:
strncpy(rdev_p->dev_name, rdev_p->t3cdev_p->name,
                        T3_MAX_DEV_NAME_LEN - 1);

But the kzalloc should mean that there will not be a problem to switch
to strlcpy ..

Do we agree, I'll make a new path with strlcpy?


I have run a static code analysis programs cppcheck, including finding
this type of problem.
But since I noticed that there were so many mistakes in addition, I
have now looked through all use of strncpy in kernel


Kind regards
Rickard Strandqvist
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