linux-kernel - Re: [PATCH] futex: Take mmap_sem for get_user_pages in fault_in_user

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 8 Dec 2009 22:26:12 +1100
From:	Nick Piggin <npiggin@...e.de>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	akpm@...l.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	dvhltc@...ibm.com, stable@...nel.org
Subject: Re: [PATCH] futex: Take mmap_sem for get_user_pages in
	fault_in_user_writeable

On Tue, Dec 08, 2009 at 01:19:42PM +0100, Andi Kleen wrote:
> futex: Take mmap_sem for get_user_pages in fault_in_user_writeable
> 
> gup() requires mmap_sem, so take it before running it. The
> recent fault_in_user_writeable() didn't do that.
> 
> I didn't find a good futex test case, so untested.
> 
> Likely a stable candidate.
> 
> Cc: npiggin@...e.de
> Cc: tglx@...utronix.de
> Cc: dvhltc@...ibm.com
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>

I agree it should go to .stable.

Acked-by: Nick Piggin <npiggin@...e.de>


> ---
>  kernel/futex.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6.32-ak/kernel/futex.c
> ===================================================================
> --- linux-2.6.32-ak.orig/kernel/futex.c
> +++ linux-2.6.32-ak/kernel/futex.c
> @@ -304,8 +304,13 @@ void put_futex_key(int fshared, union fu
>   */
>  static int fault_in_user_writeable(u32 __user *uaddr)
>  {
> -	int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
> +	int ret;
> +	struct mm_struct *mm = current->mm;
> +
> +	down_read(&mm->mmap_sem);
> +	ret = get_user_pages(current, mm, (unsigned long)uaddr,
>  				 1, 1, 0, NULL, NULL);
> +	up_read(&mm->mmap_sem);
>  	return ret < 0 ? ret : 0;
>  }
>  
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/