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From: Bruce Richardson <bruce.richardson@intel.com>
To: "Wiles, Keith" <keith.wiles@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 0/5] clean up snprintf use for string copying
Date: Wed, 3 Apr 2019 16:13:49 +0100	[thread overview]
Message-ID: <20190403151349.GA1325@bricha3-MOBL.ger.corp.intel.com> (raw)
Message-ID: <20190403151349.9IyQ0HEYExsfh5XvDPE9Yt6yHoJIqzI7btd3FTEcreo@z> (raw)
In-Reply-To: <5F7D9EB2-AD8D-475B-852C-D8B25475F25C@intel.com>

On Wed, Apr 03, 2019 at 03:57:49PM +0100, Wiles, Keith wrote:
> 
> 
> > On Apr 3, 2019, at 9:45 AM, Bruce Richardson <bruce.richardson@intel.com> wrote:
> > 
> > There are quite a few instances remaining in DPDK where snprintf is being
> > used for string copying. These were not being picked up by our existing
> > coccinelle script, but that can be fixed by editing the script and running
> > it against our code. In the process a bug was found and fixed in the
> > bonding pmd, where we were incorrectly specifiying the buffer length
> > parameter to snprintf.
> > 
> > The actual replacement was done in two phases - first replacing all
> > instances where only the snprintf line in question needed changing, then
> > fixing the other instances where we also needed to add in the header
> > include. [Using two stages allowed the header addition to be automated too,
> > since we had a list of files where every one needed the header inclusion]
> > 
> > 
> > Bruce Richardson (5):
> >  net/bonding: fix buffer length when printing strings
> >  devtools/cocci: make strlcpy replacement smarter
> >  devtools/cocci: create safer version of strlcpy script
> >  replace snprintf with strlcpy without adding extra include
> >  replace snprintf with strlcpy
> > 
> 
> Should we not be testing the return values from strlcpy and snprintf, which means we need to create a macro or inline function. We could use a macro and only enable with DEBUG support if we think performance or code size if a problem.
> 

Yes, I think in some/many cases we should be checking the return value, but
unfortunately I don't think it's the case that we always should or should
not do so. In some cases, truncation is fine. Therefore, I don't think an
automated solution can work here, and I don't see much point in wrapping
any of these functions in macros, since the action to take on truncation
probably varies from place to place.

> I am surprised none of the tools are catching these types of problems.
> 
Yes. It would be useful to have a tool to flag this, so we can see under
what circumstances it may be a problem.

> Not to make Bruce do that change for this patch, but we need to look at it for a later patch IMO.
> 
Phew! :-)

  parent reply	other threads:[~2019-04-03 15:13 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-03 14:45 Bruce Richardson
2019-04-03 14:45 ` Bruce Richardson
2019-04-03 14:45 ` [dpdk-dev] [PATCH 1/5] net/bonding: fix buffer length when printing strings Bruce Richardson
2019-04-03 14:45   ` Bruce Richardson
2019-04-03 15:47   ` Stephen Hemminger
2019-04-03 15:47     ` Stephen Hemminger
2019-04-03 15:51     ` Bruce Richardson
2019-04-03 15:51       ` Bruce Richardson
2019-04-03 15:53       ` Stephen Hemminger
2019-04-03 15:53         ` Stephen Hemminger
2019-04-03 14:45 ` [dpdk-dev] [PATCH 2/5] devtools/cocci: make strlcpy replacement smarter Bruce Richardson
2019-04-03 14:45   ` Bruce Richardson
2019-04-03 14:45 ` [dpdk-dev] [PATCH 3/5] devtools/cocci: create safer version of strlcpy script Bruce Richardson
2019-04-03 14:45   ` Bruce Richardson
2019-04-03 14:45 ` [dpdk-dev] [PATCH 4/5] replace snprintf with strlcpy without adding extra include Bruce Richardson
2019-04-03 14:45   ` Bruce Richardson
2019-04-03 15:51   ` Stephen Hemminger
2019-04-03 15:51     ` Stephen Hemminger
2019-04-03 15:56     ` Bruce Richardson
2019-04-03 15:56       ` Bruce Richardson
2019-04-04 18:05       ` Thomas Monjalon
2019-04-04 18:05         ` Thomas Monjalon
2019-04-03 14:45 ` [dpdk-dev] [PATCH 5/5] replace snprintf with strlcpy Bruce Richardson
2019-04-03 14:45   ` Bruce Richardson
2019-04-03 14:57 ` [dpdk-dev] [PATCH 0/5] clean up snprintf use for string copying Wiles, Keith
2019-04-03 14:57   ` Wiles, Keith
2019-04-03 15:13   ` Bruce Richardson [this message]
2019-04-03 15:13     ` Bruce Richardson
2019-04-03 15:27   ` Stephen Hemminger
2019-04-03 15:27     ` Stephen Hemminger
2019-04-04 20:11 ` Thomas Monjalon
2019-04-04 20:11   ` Thomas Monjalon

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