Re: [PATCH v6 2/7] fpga: sec-mgr: enable secure updates

["Martin Hundebøll" <mhu@silicom.dk>]

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Hi Russ,

On 01/12/2020 00.54, Russ Weight wrote:
> Thanks Martin. I'll work on a fix for this.

Attached is my in-house fix.

// Martin

> On 11/26/20 6:02 AM, Martin Hundebøll wrote:
>> Hi Russ,
>>
>> I found another thing while testing this...
>>
>> On 06/11/2020 02.09, Russ Weight wrote:
>>
>> <snip>
>>
>>> +static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
>>> +                  const char *buf, size_t count)
>>> +{
>>> +    struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
>>> +    int ret = count;
>>> +
>>> +    if (count == 0 || count >= PATH_MAX)
>>> +        return -EINVAL;
>>> +
>>> +    mutex_lock(&smgr->lock);
>>> +    if (smgr->driver_unload || smgr->progress != FPGA_SEC_PROG_IDLE) {
>>> +        ret = -EBUSY;
>>> +        goto unlock_exit;
>>> +    }
>>> +
>>> +    smgr->filename = kstrndup(buf, count - 1, GFP_KERNEL);
>>
>> The `count - 1` is meant to remove a trailing newline, but opae-sdk writes the filename without newline, so better do it conditionally...
>>
>>> +    if (!smgr->filename) {
>>> +        ret = -ENOMEM;
>>> +        goto unlock_exit;
>>> +    }
>>> +
>>> +    smgr->err_code = FPGA_SEC_ERR_NONE;
>>> +    smgr->progress = FPGA_SEC_PROG_READING;
>>> +    reinit_completion(&smgr->update_done);
>>> +    schedule_work(&smgr->work);
>>> +
>>> +unlock_exit:
>>> +    mutex_unlock(&smgr->lock);
>>> +    return ret;
>>> +}
>>> +static DEVICE_ATTR_WO(filename);
>>> +
>>> +static struct attribute *sec_mgr_update_attrs[] = {
>>> +    &dev_attr_filename.attr,
>>> +    NULL,
>>> +};
>>
>> Thanks,
>> Martin
> 

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From 23113231c7819b2e99854cac1ec4370b06db442c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Hundeb=C3=B8ll?= <mhu@silicom.dk>
Date: Thu, 26 Nov 2020 14:19:51 +0100
Subject: [PATCH] fpga: fpga-sec-mgr: handle trailing newline in filename_store
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The copying of the filename written to the sysfs unconditionally remove
the last character, as (I assume) if it were a newline char. For the
most cases this is true (e.g. when using `echo` in the shell), but some
software writes the filename without a trailing newline, in which the
firmware load obviously fails.

Fix this by checking for a newline char, and replacing it with '\0' if
found.

Fixes: 1815cc58d473 ("fpga: sec-mgr: enable secure updates")
Signed-off-by: Martin Hundebøll <mhu@silicom.dk>
---
 drivers/fpga/fpga-sec-mgr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
index 72b61dc173db..d2ce4c682bd9 100644
--- a/drivers/fpga/fpga-sec-mgr.c
+++ b/drivers/fpga/fpga-sec-mgr.c
@@ -423,12 +423,16 @@ static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
 		goto unlock_exit;
 	}
 
-	smgr->filename = kstrndup(buf, count - 1, GFP_KERNEL);
+	smgr->filename = kstrndup(buf, count, GFP_KERNEL);
 	if (!smgr->filename) {
 		ret = -ENOMEM;
 		goto unlock_exit;
 	}
 
+	/* remove trailing newline */
+	if (smgr->filename[count - 1] == '\n')
+		smgr->filename[count - 1] = '\0';
+
 	smgr->err_code = FPGA_SEC_ERR_NONE;
 	smgr->hw_errinfo = 0;
 	smgr->request_cancel = false;
-- 
2.29.2