linux-kernel - Re: siginfo memory leak?

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Date:	Mon, 23 May 2016 15:05:38 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:	Oleg Nesterov <oleg@...hat.com>, Aleksa Sarai <asarai@...e.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	linux-s390@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: siginfo memory leak?

On Mon 23-05-16 14:43:19, Martin Schwidefsky wrote:
> On Mon, 23 May 2016 13:16:30 +0200
[...]
> > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
> > index 791a4146052c..41913fac14e4 100644
> > --- a/arch/s390/mm/fault.c
> > +++ b/arch/s390/mm/fault.c
> > @@ -248,6 +248,7 @@ static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
> >  	si.si_signo = SIGSEGV;
> >  	si.si_code = si_code;
> >  	si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
> > +	si.si_errno = 0;
> >  	force_sig_info(SIGSEGV, &si, current);
> >  }
> > 
> 
> The other for place where s390 calls force_sig_info are correct.
> Only do_sigsegv misses the clear of si_errno.

I can send a full patch with the proper changelog but I am really
wondering whether we can plug this in a more systematic way. If you
prefer a small s390 specific I will do it right away though. Same
applies to x86 one.
 
> > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> > index ade185a46b1d..f8b66ddbb47d 100644
> > --- a/arch/x86/kernel/traps.c
> > +++ b/arch/x86/kernel/traps.c
> > @@ -286,6 +286,7 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
> > 
> >  	if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
> >  			NOTIFY_STOP) {
> > +		memset(&info, 0, sizeof(info));
> >  		conditional_sti(regs);
> >  		do_trap(trapnr, signr, str, regs, error_code,
> >  			fill_trap_info(regs, signr, trapnr, &info));
> > 
> 
> -- 
> blue skies,
>    Martin.
> 
> "Reality continues to ruin my life." - Calvin.

-- 
Michal Hocko
SUSE Labs