2017-04-28 12:49:37

by Ding Tianhong

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

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 <[email protected]>
---
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

2017-04-28 13:16:52

by Sabrina Dubroca

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

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 <[email protected]>
> ---
> 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

2017-04-28 13:52:03

by David Laight

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

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

2017-04-29 02:13:33

by Ding Tianhong

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

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 <[email protected]>
>> ---
>> 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
>>
>