linux-kernel - Re: [PATCH BUGFIX] [RESEND] mm: Pass mm->flags as a coredump parameter for consistency

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Date:	Mon, 21 Dec 2009 10:53:39 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Masami Hiramatsu <mhiramat@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	lkml <linux-kernel@...r.kernel.org>,
	systemtap <systemtap@...rces.redhat.com>,
	DLE <dle-develop@...ts.sourceforge.net>,
	Roland McGrath <roland@...hat.com>,
	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH BUGFIX] [RESEND] mm: Pass mm->flags as a coredump parameter for consistency

> Pass mm->flags as a coredump parameter for consistency.
> 
>  ---
> 1787         if (mm->core_state || !get_dumpable(mm)) {  <- (1)
> 1788                 up_write(&mm->mmap_sem);
> 1789                 put_cred(cred);
> 1790                 goto fail;
> 1791         }
> 1792
> [...]
> 1798         if (get_dumpable(mm) == 2) {    /* Setuid core dump mode */ <-(2)
> 1799                 flag = O_EXCL;          /* Stop rewrite attacks */
> 1800                 cred->fsuid = 0;        /* Dump root private */
> 1801         }
>  ---
> 
> Since dumpable bits are not protected by lock, there is a
> chance to change these bits between (1) and (2).
> 
> To solve this issue, this patch copies mm->flags to
> coredump_params.mm_flags at the beginning of do_coredump()                      and uses it instead of get_dumpable() while dumping core.
> 
> This copy is also passed to binfmt->core_dump, since
> elf*_core_dump() uses dump_filter bits in mm->flags.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
> Cc: Roland McGrath <roland@...hat.com>
> Cc: Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Oleg Nesterov <oleg@...hat.com>
> Cc: Ingo Molnar <mingo@...e.hu>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

looks good to me.
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>




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