From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: David Hunt <david.hunt@intel.com>, dev@dpdk.org, stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2] examples/vm_power_manager: fix string null termination
Date: Fri, 26 Apr 2019 13:47:41 +0100 [thread overview]
Message-ID: <adc81ddc-a1f6-d651-a785-e1f9f2c8372c@intel.com> (raw)
Message-ID: <20190426124741.eK42r1P4C_8b5KaTpiQnEVNiHhpIcME1CGjeGegf6hA@z> (raw)
In-Reply-To: <20190426123117.GA1695@bricha3-MOBL.ger.corp.intel.com>
On 26-Apr-19 1:31 PM, Bruce Richardson wrote:
> On Fri, Apr 26, 2019 at 12:56:08PM +0100, Burakov, Anatoly wrote:
>> On 26-Apr-19 12:24 PM, David Hunt wrote:
>>> coverity complains about a null-termination after a read,
>>> so we terminate after exiting the do-while loop. The position
>>> is conditional on whether idx is within the buffer or at the
>>> end of the buffer.
>>>
>>> Coverity issue: 337680
>>> Fixes: a63504a90f ("examples/power: add JSON string handling")
>>> CC: stable@dpdk.org
>>>
>>> Signed-off-by: David Hunt <david.hunt@intel.com>
>>>
>>> ---
>>> v2:
>>> * Move null termination outside of do-while.
>>> ---
>>> examples/vm_power_manager/channel_monitor.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/examples/vm_power_manager/channel_monitor.c b/examples/vm_power_manager/channel_monitor.c
>>> index 971e4f2bc..03fdcd15a 100644
>>> --- a/examples/vm_power_manager/channel_monitor.c
>>> +++ b/examples/vm_power_manager/channel_monitor.c
>>> @@ -822,6 +822,8 @@ read_json_packet(struct channel_info *chan_info)
>>> break;
>>> } while (indent > 0);
>>> + json_data[idx + (idx < MAX_JSON_STRING_LEN - 1)] = '\0';
>>> +
>>
>> I don't think you need this complicated logic here. You start at idx = 0, so
>> even if you receive 0 bytes, you'll terminate buffer at index 0. You also
>> break when idx reaches (MAX_JSON_STRING_LEN - 1), so it's also safe to do
>> json_data[idx] after the loop. In all other cases, you still increment idx
>> before breaking out (e.g. when reaching indent == 0), so it's also safe to
>> do json_data[idx] in those cases.
>>
> +1 to that.
>
> An alternative and simpler option might be to memset the who array to zero
> before you start anyway.
That'll cost us few extra cycles on a non-performance critical path full
of syscalls, surely we can't have that! :)
>
> /Bruce
>
--
Thanks,
Anatoly
next prev parent reply other threads:[~2019-04-26 12:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 8:43 [dpdk-dev] [PATCH v1] " David Hunt
2019-04-26 8:43 ` David Hunt
2019-04-26 10:33 ` Burakov, Anatoly
2019-04-26 10:33 ` Burakov, Anatoly
2019-04-26 11:16 ` Hunt, David
2019-04-26 11:16 ` Hunt, David
2019-04-26 11:24 ` [dpdk-dev] [PATCH v2] " David Hunt
2019-04-26 11:24 ` David Hunt
2019-04-26 11:56 ` Burakov, Anatoly
2019-04-26 11:56 ` Burakov, Anatoly
2019-04-26 12:31 ` Bruce Richardson
2019-04-26 12:31 ` Bruce Richardson
2019-04-26 12:47 ` Burakov, Anatoly [this message]
2019-04-26 12:47 ` Burakov, Anatoly
2019-04-26 14:04 ` [dpdk-dev] [PATCH v3] " David Hunt
2019-04-26 14:04 ` David Hunt
2019-04-26 14:10 ` Burakov, Anatoly
2019-04-26 14:10 ` Burakov, Anatoly
2019-05-02 23:43 ` Thomas Monjalon
2019-05-02 23:43 ` Thomas Monjalon
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