[PATCH v3] iov_iter: don't revert iov buffer if csum error

[PATCH v3] iov_iter: don't revert iov buffer if csum error

[Ding Tianhong]

The patch 327868212381 (make skb_copy_datagram_msg() et.al. preserve
->msg_iter on error) will revert the iov buffer if copy to iter
failed, but it didn't copy any datagram if the skb_checksum_complete
error, so no need to revert any data at this place.

v2: Sabrina notice that return -EFAULT when checksum error is not correct
    here, it would confuse the caller about the return value, so fix it.

v3: According AI's suggestion, directly return -EINVAL when __skb_checksum_complete()
    return error is a more simple solution.

Fixes: 327868212381 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@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 0306543..726bf8a 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -719,7 +719,7 @@ 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;
+			return -EINVAL;
 		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
 			goto fault;
 	} else {
-- 
1.8.3.1

Re: [PATCH v3] iov_iter: don't revert iov buffer if csum error

[Al Viro]

On Wed, May 03, 2017 at 03:02:32PM +0800, Ding Tianhong wrote:
> The patch 327868212381 (make skb_copy_datagram_msg() et.al. preserve
> ->msg_iter on error) will revert the iov buffer if copy to iter
> failed, but it didn't copy any datagram if the skb_checksum_complete
> error, so no need to revert any data at this place.

See a6a5993243550b09f620941dea741b7421fdf79c in mainline...

Miss it//Re: [PATCH v3] iov_iter: don't revert iov buffer if csum error

[Ding Tianhong]

Miss it, it is already in the kernel tree, sorry for the noisy.

On 2017/5/3 15:02, Ding Tianhong wrote:
> The patch 327868212381 (make skb_copy_datagram_msg() et.al. preserve
> ->msg_iter on error) will revert the iov buffer if copy to iter
> failed, but it didn't copy any datagram if the skb_checksum_complete
> error, so no need to revert any data at this place.
> 
> v2: Sabrina notice that return -EFAULT when checksum error is not correct
>     here, it would confuse the caller about the return value, so fix it.
> 
> v3: According AI's suggestion, directly return -EINVAL when __skb_checksum_complete()
>     return error is a more simple solution.
> 
> Fixes: 327868212381 ("make skb_copy_datagram_msg() et.al. preserve->msg_iter on error")
> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> Signed-off-by: Wei Yongjun <weiyongjun1@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 0306543..726bf8a 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -719,7 +719,7 @@ 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;
> +			return -EINVAL;
>  		if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
>  			goto fault;
>  	} else {
>