netdev - Re: [PATCH ethtool] ethtool: Fix uninitialized variable use at qsfp dump

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Date:   Tue, 2 Oct 2018 07:17:56 +0000
From:   Eran Ben Elisha <eranbe@...lanox.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "John W. Linville" <linville@...driver.com>,
        Chris Preimesberger <chrisp@...nsition.com>,
        Neil Horman <nhorman@...driver.com>,
        Vidya Sagar Ravipati <vidya@...ulusnetworks.com>
Subject: Re: [PATCH ethtool] ethtool: Fix uninitialized variable use at qsfp
 dump



On 9/27/2018 7:08 PM, Andrew Lunn wrote:
> On Thu, Sep 27, 2018 at 04:48:35PM +0300, Eran Ben Elisha wrote:
>> Struct sff_diags can be used uninitialized at sff8636_show_dom, this
>> caused the tool to show unreported fields (supports_alarms) by the lower
>> level driver.
>>
>> Fixes: a5e73bb05ee4 ("ethtool:QSFP Plus/QSFP28 Diagnostics Information Support")
>> Signed-off-by: Eran Ben Elisha <eranbe@...lanox.com>
>> ---
>>   qsfp.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/qsfp.c b/qsfp.c
>> index 32e195d12dc0..d196aa1753de 100644
>> --- a/qsfp.c
>> +++ b/qsfp.c
>> @@ -671,7 +671,7 @@ static void sff8636_dom_parse(const __u8 *id, struct sff_diags *sd)
>>   
>>   static void sff8636_show_dom(const __u8 *id, __u32 eeprom_len)
>>   {
>> -	struct sff_diags sd;
>> +	struct sff_diags sd = {0};
>>   	char *rx_power_string = NULL;
>>   	char power_string[MAX_DESC_SIZE];
>>   	int i;
> 
> Hi Erin
> 
> I wonder if similar bugs happen in sfpdiag.c?

Bug is not present here, all sd needed fields are being filled in 
sff8472_parse_eeprom right at the beginning.

> 
> void sff8472_show_all(const __u8 *id)
> {
>          struct sff_diags sd;
>          char *rx_power_string = NULL;
>          int i;
> 
> sd is also on the stack and not initialised. Could you expand your
> patch to also clear this one as well, just to be safe.

Although bug is not present, I agree that better initialize it to be on 
the safe side. will post soon.

Eran

> 
> Thanks
> 	Andrew
>