[dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not terminated

Maxime Coquelin maxime.coquelin at redhat.com
Thu Oct 5 14:42:24 CEST 2017



On 10/05/2017 02:35 PM, Piasecki, JacekX wrote:
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin at redhat.com]
> Sent: Monday, 2 October, 2017 17:07
> To: Jastrzebski, MichalX K <michalx.k.jastrzebski at intel.com>; yliu at fridaylinux.org
> Cc: dev at dpdk.org; Jain, Deepak K <deepak.k.jain at intel.com>; Piasecki, JacekX <jacekx.piasecki at intel.com>; Liu, Changpeng <changpeng.liu at intel.com>; stable at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not terminated
> 
> 
> 
> On 10/02/2017 03:50 PM, Jastrzebski, MichalX K wrote:
>>> -----Original Message-----
>>> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Michal
>>> Jastrzebski
>>> Sent: Friday, September 22, 2017 3:08 PM
>>> To: yliu at fridaylinux.org; maxime.coquelin at redhat.com
>>> Cc: dev at dpdk.org; Jain, Deepak K <deepak.k.jain at intel.com>; Piasecki,
>>> JacekX <jacekx.piasecki at intel.com>; Liu, Changpeng
>>> <changpeng.liu at intel.com>; stable at dpdk.org
>>> Subject: [dpdk-dev] [PATCH] examples/vhost_scsi: fix buffer not
>>> terminated
>>>
>>> From: Jacek Piasecki <jacekx.piasecki at intel.com>
>>>
>>> Fix size of buffer in strcpy. There was possible to get not
>>> terminated string after copy operation.
>>>
>>> Coverity issue: 158631
>>> Fixes: db75c7af19bb ("examples/vhost_scsi: introduce a new sample
>>> app")
>>> Cc: changpeng.liu at intel.com
>>> Cc: stable at dpdk.org
>>>
>>> Signed-off-by: Jacek Piasecki <jacekx.piasecki at intel.com>
>>> ---
>>>    examples/vhost_scsi/scsi.c | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/examples/vhost_scsi/scsi.c b/examples/vhost_scsi/scsi.c
>>> index 54d3104..de9639a 100644
>>> --- a/examples/vhost_scsi/scsi.c
>>> +++ b/examples/vhost_scsi/scsi.c
>>> @@ -307,7 +307,8 @@
>>>    		strncpy((char *)inqdata->t10_vendor_id, "INTEL", 8);
>>>
>>>    		/* PRODUCT IDENTIFICATION */
>>> -		strncpy((char *)inqdata->product_id, bdev->product_name,
>>> 16);
>>> +		strncpy((char *)inqdata->product_id, bdev->product_name,
>>> +				ARRAY_SIZE(inqdata->product_id) - 1);
> 
> Does it assume that product_id is memzero'ed before?
> IIUC strncpy manpage, it wouldn't protect against non-null terminated strings if it is not the case:
> 
> Yes, I assumed that this area is zeroed before strncpy. Earlier there is a casting from *task to *inqdata (*task is zmalloced).
Ok. I think the assumption is dangerous.

> To be sure that the destination area is clear I propose to add:
> memset(inqdata->product_id, 0, ARRAY_SIZE(inqdata->product_id));
> before strncpy. Would that be OK?

Or call strncpy with ARRAY_SIZE(inqdata->product_id) as max length,
and then do
inqdata->product_id[ARRAY_SIZE(inqdata->product_id) - 1] = '\0';

Regards,
Maxime
> 
> Regards,
> Jacek
> 
>>>
>>>    		/* PRODUCT REVISION LEVEL */
>>>    		strncpy((char *)inqdata->product_rev, "0001", 4);
>>> --
>>> 1.9.1
>>
>> Hi Yu / Maxime,
>> I would like to ask for a feedback regarding proposed fix.
>> If everything is ok with it, please send acked-by.
>>
>> Best regards
>> Michal.
>>


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