netdev - RE: [patch iproute2 1/2] tc: action: fix crash caused by incorrect *argv check

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Message-ID: <48a250ba23394bdba024cd493717cb55@AcuMS.aculab.com>
Date:   Wed, 24 Jul 2019 09:07:58 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Stephen Hemminger' <stephen@...workplumber.org>,
        Jiri Pirko <jiri@...nulli.us>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "sthemmin@...rosoft.com" <sthemmin@...rosoft.com>,
        "dsahern@...il.com" <dsahern@...il.com>,
        "alexanderk@...lanox.com" <alexanderk@...lanox.com>,
        "mlxsw@...lanox.com" <mlxsw@...lanox.com>
Subject: RE: [patch iproute2 1/2] tc: action: fix crash caused by incorrect
 *argv check

From: Stephen Hemminger
> Sent: 23 July 2019 18:54
> 
> On Tue, 23 Jul 2019 13:25:37 +0200
> Jiri Pirko <jiri@...nulli.us> wrote:
> 
> > From: Jiri Pirko <jiri@...lanox.com>
> >
> > One cannot depend on *argv being null in case of no arg is left on the
> > command line. For example in batch mode, this is not always true. Check
> > argc instead to prevent crash.

Hmmm... expecting the increments of argv and decrements of argc to match
it probably wishful thinking....
A lot of parsers don't even look at argc.

> Actually makeargs does NULL terminate the last arg so what input
> to batchmode is breaking this?

The 'usual' problem is an extra increment of argv because the last entry
was something that 'eats' two or more entries.

	David

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