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From: Bruce Richardson <bruce.richardson@intel.com>
To: "Burakov, Anatoly" <anatoly.burakov@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 13:31:17 +0100	[thread overview]
Message-ID: <20190426123117.GA1695@bricha3-MOBL.ger.corp.intel.com> (raw)
Message-ID: <20190426123117.xGz7lDsfjP77Rn3bKBBSV7aPSFS1o9LPtUUBvckCPds@z> (raw)
In-Reply-To: <339cb6ac-9c56-b9cb-28e8-950ad2cd70b4@intel.com>

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.

/Bruce

  parent reply	other threads:[~2019-04-26 12:31 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 [this message]
2019-04-26 12:31       ` Bruce Richardson
2019-04-26 12:47       ` Burakov, Anatoly
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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