linux-kernel - Re: [PATCH] scsi: qedf: Avoid reading past end of buffer

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Date:   Fri, 5 May 2017 16:10:53 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Bart Van Assche <Bart.VanAssche@...disk.com>
Cc:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "QLogic-Storage-Upstream@...ium.com" 
        <QLogic-Storage-Upstream@...ium.com>,
        "danielmicay@...il.com" <danielmicay@...il.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>
Subject: Re: [PATCH] scsi: qedf: Avoid reading past end of buffer

On Fri, May 5, 2017 at 4:01 PM, Bart Van Assche
<Bart.VanAssche@...disk.com> wrote:
> On Fri, 2017-05-05 at 15:42 -0700, Kees Cook wrote:
>> diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
>> index cceddd995a4b..a5c97342fd5d 100644
>> --- a/drivers/scsi/qedf/qedf_main.c
>> +++ b/drivers/scsi/qedf/qedf_main.c
>> @@ -2895,7 +2895,7 @@ static int __qedf_probe(struct pci_dev *pdev, int mode)
>>       slowpath_params.drv_minor = QEDF_DRIVER_MINOR_VER;
>>       slowpath_params.drv_rev = QEDF_DRIVER_REV_VER;
>>       slowpath_params.drv_eng = QEDF_DRIVER_ENG_VER;
>> -     memcpy(slowpath_params.name, "qedf", QED_DRV_VER_STR_SIZE);
>> +     strncpy(slowpath_params.name, "qedf", QED_DRV_VER_STR_SIZE);
>>       rc = qed_ops->common->slowpath_start(qedf->cdev, &slowpath_params);
>>       if (rc) {
>>               QEDF_ERR(&(qedf->dbg_ctx), "Cannot start slowpath.\n");
>
> Hello Kees,
>
> Although this patch looks fine to me, isn't strlcpy() preferred over strncpy()?

strlcpy doesn't zero-pad, so I think strncpy is preferred here,
otherwise we may risk leaving portions of the destination buffer
filled with uninitialized data, maybe leaking kernel memory contents.

-Kees

-- 
Kees Cook
Pixel Security