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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Keith Busch <keith.busch@intel.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Kees Cook <keescook@chromium.org>,
	YueHaibing <yuehaibing@huawei.com>,
	linux-mm@kvack.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] mm/gup_benchmark: prevent integer overflow in ioctl
Date: Thu, 25 Oct 2018 07:32:29 +0000	[thread overview]
Message-ID: <20181025073229.dbsloufbem4p4arz@kshutemo-mobl1> (raw)
In-Reply-To: <20181025061546.hnhkv33diogf2uis@kili.mountain>

On Thu, Oct 25, 2018 at 09:15:46AM +0300, Dan Carpenter wrote:
> The concern here is that "gup->size" is a u64 and "nr_pages" is unsigned
> long.  On 32 bit systems we could trick the kernel into allocating fewer
> pages than expected.
> 
> Fixes: 64c349f4ae78 ("mm: add infrastructure for get_user_pages_fast() benchmarking")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  mm/gup_benchmark.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
> index debf11388a60..5b42d3d4b60a 100644
> --- a/mm/gup_benchmark.c
> +++ b/mm/gup_benchmark.c
> @@ -27,6 +27,9 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  	int nr;
>  	struct page **pages;
>  
> +	if (gup->size > ULONG_MAX)
> +		return -EINVAL;
> +

Strictly speaking gup->size / PAGE_SIZE has to be <= ULONG_MAX, but it
should be fine this way too.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov

WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Keith Busch <keith.busch@intel.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Kees Cook <keescook@chromium.org>,
	YueHaibing <yuehaibing@huawei.com>,
	linux-mm@kvack.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] mm/gup_benchmark: prevent integer overflow in ioctl
Date: Thu, 25 Oct 2018 10:32:29 +0300	[thread overview]
Message-ID: <20181025073229.dbsloufbem4p4arz@kshutemo-mobl1> (raw)
In-Reply-To: <20181025061546.hnhkv33diogf2uis@kili.mountain>

On Thu, Oct 25, 2018 at 09:15:46AM +0300, Dan Carpenter wrote:
> The concern here is that "gup->size" is a u64 and "nr_pages" is unsigned
> long.  On 32 bit systems we could trick the kernel into allocating fewer
> pages than expected.
> 
> Fixes: 64c349f4ae78 ("mm: add infrastructure for get_user_pages_fast() benchmarking")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  mm/gup_benchmark.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
> index debf11388a60..5b42d3d4b60a 100644
> --- a/mm/gup_benchmark.c
> +++ b/mm/gup_benchmark.c
> @@ -27,6 +27,9 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  	int nr;
>  	struct page **pages;
>  
> +	if (gup->size > ULONG_MAX)
> +		return -EINVAL;
> +

Strictly speaking gup->size / PAGE_SIZE has to be <= ULONG_MAX, but it
should be fine this way too.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov

  reply	other threads:[~2018-10-25  7:32 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-25  6:15 [PATCH] mm/gup_benchmark: prevent integer overflow in ioctl Dan Carpenter
2018-10-25  6:15 ` Dan Carpenter
2018-10-25  7:32 ` Kirill A. Shutemov [this message]
2018-10-25  7:32   ` Kirill A. Shutemov
2018-11-01  6:38 ` William Kucharski
2018-11-01  6:38   ` William Kucharski
2018-11-01  7:16   ` Dan Carpenter
2018-11-01  7:16     ` Dan Carpenter
2018-11-01  8:28     ` William Kucharski
2018-11-01  8:28       ` William Kucharski

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