linux-kernel - Re: [PATCH] proc: Fix uninitialized byte read in get_mm

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Date:   Fri, 12 Jul 2019 20:46:32 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Alexey Izbyshev <izbyshev@...ras.ru>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, security@...nel.org
Subject: Re: [PATCH] proc: Fix uninitialized byte read in get_mm_cmdline()

On Fri, Jul 12, 2019 at 06:36:26PM +0200, Oleg Nesterov wrote:
> On 07/12, Alexey Izbyshev wrote:
> >
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -275,6 +275,8 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
> >  		if (got <= offset)
> >  			break;
> >  		got -= offset;
> > +		if (got < size)
> > +			size = got;
> 
> Acked-by: Oleg Nesterov <oleg@...hat.com>

The proper fix to all /proc/*/cmdline problems is to revert

	f5b65348fd77839b50e79bc0a5e536832ea52d8d
	proc: fix missing final NUL in get_mm_cmdline() rewrite

	5ab8271899658042fabc5ae7e6a99066a210bc0e
	fs/proc: simplify and clarify get_mm_cmdline() function