[PATCH] iov_iter: don't revert if csum error

[PATCH] iov_iter: don't revert if csum error

[Ding Tianhong]

The patch 3278682 (make skb_copy_datagram_msg() et.al. preserve
->msg_iter on error) will revert the iov buffer if copy to iter
failed, but it looks no need to revert for csum error, so fix it.

Fixes: 3278682 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
---
 net/core/datagram.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/datagram.c b/net/core/datagram.c
index f4947e7..475a8e9 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -760,7 +760,7 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,

 	if (msg_data_left(msg) < chunk) {
 		if (__skb_checksum_complete(skb))
-			goto csum_error;
+			goto fault;
 		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
 			goto fault;
 	} else {
-- 
1.8.3.1

Re: [PATCH] iov_iter: don't revert if csum error

[Sabrina Dubroca]

2017-04-28, 20:48:45 +0800, Ding Tianhong wrote:
> The patch 3278682 (make skb_copy_datagram_msg() et.al. preserve
> ->msg_iter on error) will revert the iov buffer if copy to iter
> failed, but it looks no need to revert for csum error, so fix it.
> 
> Fixes: 3278682 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")

Please use 12 digits, ie 327868212381.

> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> ---
>  net/core/datagram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/datagram.c b/net/core/datagram.c
> index f4947e7..475a8e9 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -760,7 +760,7 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
> 
>  	if (msg_data_left(msg) < chunk) {
>  		if (__skb_checksum_complete(skb))
> -			goto csum_error;
> +			goto fault;

With this patch, skb_copy_and_csum_datagram_msg() will return -EFAULT
for an incorrect checksum, that doesn't seem right.

>  		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
>  			goto fault;
>  	} else {
> -- 
> 1.8.3.1
> 

-- 
Sabrina

RE: [PATCH] iov_iter: don't revert if csum error

[David Laight]

From: Sabrina Dubroca
> Sent: 28 April 2017 14:17
...
> >  		if (__skb_checksum_complete(skb))
> > -			goto csum_error;
> > +			goto fault;
> 
> With this patch, skb_copy_and_csum_datagram_msg() will return -EFAULT
> for an incorrect checksum, that doesn't seem right.

Especially since (IIRC) -EFAULT generates SIGSEGV.

	David

Re: [PATCH] iov_iter: don't revert if csum error

[Ding Tianhong]

On 2017/4/28 21:16, Sabrina Dubroca wrote:
> 2017-04-28, 20:48:45 +0800, Ding Tianhong wrote:
>> The patch 3278682 (make skb_copy_datagram_msg() et.al. preserve
>> ->msg_iter on error) will revert the iov buffer if copy to iter
>> failed, but it looks no need to revert for csum error, so fix it.
>>
>> Fixes: 3278682 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
> 
> Please use 12 digits, ie 327868212381.
> 
>> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
>> ---
>>  net/core/datagram.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/datagram.c b/net/core/datagram.c
>> index f4947e7..475a8e9 100644
>> --- a/net/core/datagram.c
>> +++ b/net/core/datagram.c
>> @@ -760,7 +760,7 @@ int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
>>
>>  	if (msg_data_left(msg) < chunk) {
>>  		if (__skb_checksum_complete(skb))
>> -			goto csum_error;
>> +			goto fault;
> 
> With this patch, skb_copy_and_csum_datagram_msg() will return -EFAULT
> for an incorrect checksum, that doesn't seem right.
> 

Yes, should not change the return value, thanks.

Ding

>>  		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
>>  			goto fault;
>>  	} else {
>> -- 
>> 1.8.3.1
>>
>