linux-kernel - Re: [PATCH v2] mm: rmap: fix use-after-free in __put_anon

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:	Fri, 6 Jun 2014 17:30:33 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andrey Ryabinin <a.ryabinin@...sung.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, koct9i@...il.com,
	stable@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH v2] mm: rmap: fix use-after-free in __put_anon_vma

On Fri, Jun 06, 2014 at 07:09:30PM +0400, Andrey Ryabinin wrote:
> While working address sanitizer for kernel I've discovered use-after-free
> bug in __put_anon_vma.
> For the last anon_vma, anon_vma->root freed before child anon_vma.
> Later in anon_vma_free(anon_vma) we are referencing to already freed anon_vma->root
> to check rwsem.
> This patch puts freeing of child anon_vma before freeing of anon_vma->root.
> 
> Cc: <stable@...r.kernel.org> # v3.0+

Acked-by: Peter Zijlstra <peterz@...radead.org>

> Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
> ---
> 
> Changes since v1:
>  - just made it more simple following Peter's suggestion
> 
>  mm/rmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 9c3e773..cb5f70a 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1564,10 +1564,10 @@ void __put_anon_vma(struct anon_vma *anon_vma)
>  {
>  	struct anon_vma *root = anon_vma->root;
>  
> +	anon_vma_free(anon_vma);
> +
>  	if (root != anon_vma && atomic_dec_and_test(&root->refcount))
>  		anon_vma_free(root);
> -
> -	anon_vma_free(anon_vma);
>  }
>  
>  static struct anon_vma *rmap_walk_anon_lock(struct page *page,
> -- 
> 1.8.5.5
> 
--
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/