Patchwork [net] macvtap: fix recovery from gup errors

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Submitter Michael S. Tsirkin
Date June 23, 2013, 2:26 p.m.
Message ID <20130623142658.GA21141@redhat.com>
Download mbox | patch
Permalink /patch/253566/
State Accepted
Delegated to: David Miller
Headers show

Comments

Michael S. Tsirkin - June 23, 2013, 2:26 p.m.
get user pages might fail partially in macvtap zero copy
mode. To recover we need to put all pages that we got,
but code used a wrong index resulting in double-free
errors.

Reported-by: Brad Hubbard <bhubbard@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Same as the tun patch really. Also stable material.

 drivers/net/macvtap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
Jason Wang - June 24, 2013, 3:23 a.m.
On 06/23/2013 10:26 PM, Michael S. Tsirkin wrote:
> get user pages might fail partially in macvtap zero copy
> mode. To recover we need to put all pages that we got,
> but code used a wrong index resulting in double-free
> errors.
>
> Reported-by: Brad Hubbard <bhubbard@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>
> Same as the tun patch really. Also stable material.

Acked-by: Jason Wang <jasowang@redhat.com>
>
>  drivers/net/macvtap.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 59e9605..4ddd108 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -524,8 +524,9 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
>  			return -EMSGSIZE;
>  		num_pages = get_user_pages_fast(base, size, 0, &page[i]);
>  		if (num_pages != size) {
> -			for (i = 0; i < num_pages; i++)
> -				put_page(page[i]);
> +			int j;
> +			for (j = 0; j < num_pages; j++)
> +				put_page(page[i + j]);
>  			return -EFAULT;
>  		}
>  		truesize = size * PAGE_SIZE;

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David Miller - June 25, 2013, 11:24 p.m.
From: Jason Wang <jasowang@redhat.com>
Date: Mon, 24 Jun 2013 11:23:15 +0800

> On 06/23/2013 10:26 PM, Michael S. Tsirkin wrote:
>> get user pages might fail partially in macvtap zero copy
>> mode. To recover we need to put all pages that we got,
>> but code used a wrong index resulting in double-free
>> errors.
>>
>> Reported-by: Brad Hubbard <bhubbard@redhat.com>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>> ---
>>
>> Same as the tun patch really. Also stable material.
> 
> Acked-by: Jason Wang <jasowang@redhat.com>

Applied, also with the missing empty line added.
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Patch

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 59e9605..4ddd108 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -524,8 +524,9 @@  static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
 			return -EMSGSIZE;
 		num_pages = get_user_pages_fast(base, size, 0, &page[i]);
 		if (num_pages != size) {
-			for (i = 0; i < num_pages; i++)
-				put_page(page[i]);
+			int j;
+			for (j = 0; j < num_pages; j++)
+				put_page(page[i + j]);
 			return -EFAULT;
 		}
 		truesize = size * PAGE_SIZE;