From: Ken-ichirou MATSUZAWA <chamaken@gmail.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org, fw@strlen.de
Subject: Re: [PATCHv1 net-next 0/5] netlink: mmap: kernel panic and some issues
Date: Wed, 2 Sep 2015 20:35:53 +0900 [thread overview]
Message-ID: <20150902113553.GA3282@gmail.com> (raw)
In-Reply-To: <55E6C5AE.4060308@iogearbox.net>
Thank you for the reply.
On Wed, Sep 02, 2015 at 11:47:26AM +0200, Daniel Borkmann wrote:
> On 09/02/2015 02:04 AM, Ken-ichirou MATSUZAWA wrote:
> >Talking about skb_copy path, original skb's shared info is accessed
> >only in copy_skb_header, to get gso related field. As a result of
>
> It's still not correct. The thing is you can neither call skb_copy() nor
> skb_clone() on netlink mmaped skbs. For example, skb_copy_bits() would
I am sorry for the lack of explanation.
And I am afraid I misunderstand...
Updated pointers to its data area in a mmaped netlink skb is only
its tail. Head, data and end will not be updated. skb_copy() calls
int skb_copy_bits(const struct sk_buff *skb, int offset, void *to, int len)
as its argument, "offset" is always 0 and "len" is skb->len. In
skb_copy_bits() both "start" and "copy" are skb->len, which means
"len - copy" is always 0 so that retuns 0 before accessing shared
info.
I don't know the situation is intended or not, it seems that
skb_copy() for a mmaped skb will not access its shared info.
After that, copy_skb_header() will set newly allocate skb's (wrong)
gso fields, I asked we should clear it or not.
> special case. We need an own netlink_mmap_to_full_skb() handler for this,
> that copies/transforms this into a "normal" skb. I'll have a look it this
If the above situation is an unintentional, we need it to avoid a
future confusion.
Thanks,
next prev parent reply other threads:[~2015-09-02 11:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-22 13:17 [RFC PATCH 0/5] netlink: mmap kernel panic and some issues Ken-ichirou MATSUZAWA
2015-08-12 8:28 ` [PATCHv1 net-next 0/5] netlink: mmap: " Ken-ichirou MATSUZAWA
2015-08-12 8:31 ` [PATCHv1 net-next 1/5] netlink: mmap: introduce mmaped skb helper functions Ken-ichirou MATSUZAWA
2015-08-12 8:32 ` [PATCHv1 net-next 2/5] netlink: mmap: apply " Ken-ichirou MATSUZAWA
2015-08-12 8:34 ` [PATCHv1 net-next 3/5] netlink: mmap: fix status for not delivered skb Ken-ichirou MATSUZAWA
2015-08-12 8:35 ` [PATCHv1 net-next 4/5] netlink: mmap: update tx type check Ken-ichirou MATSUZAWA
2015-08-12 8:38 ` [PATCHv1 net-next 5/5] netlink: mmap: notify only when NL_MMAP_STATUS_VALID frame exists Ken-ichirou MATSUZAWA
2015-08-12 23:38 ` [PATCHv1 net-next 0/5] netlink: mmap: kernel panic and some issues David Miller
2015-08-14 8:58 ` Ken-ichirou MATSUZAWA
2015-08-14 10:01 ` Daniel Borkmann
2015-08-14 10:38 ` Daniel Borkmann
2015-08-15 2:25 ` Ken-ichirou MATSUZAWA
2015-08-17 21:02 ` David Miller
2015-08-19 14:29 ` Daniel Borkmann
2015-09-02 0:04 ` Ken-ichirou MATSUZAWA
2015-09-02 9:47 ` Daniel Borkmann
2015-09-02 11:35 ` Ken-ichirou MATSUZAWA [this message]
2015-09-02 15:56 ` Daniel Borkmann
2015-09-02 22:27 ` Ken-ichirou MATSUZAWA
2015-09-07 14:54 ` Daniel Borkmann
2015-09-09 5:59 ` David Miller
2015-09-09 8:53 ` Thomas Graf
2015-09-09 9:22 ` Daniel Borkmann
2015-08-20 3:43 ` [PATCH net] netlink: mmap: fix tx type check Ken-ichirou MATSUZAWA
2015-08-23 23:06 ` David Miller
2015-08-20 5:54 ` [PATCH net] netlink: rx mmap: fix POLLIN condition Ken-ichirou MATSUZAWA
2015-08-26 3:17 ` David Miller
2015-08-28 7:00 ` Ken-ichirou MATSUZAWA
2015-08-28 7:05 ` [PATCH net] netlink: mmap: fix lookup frame position Ken-ichirou MATSUZAWA
2015-08-29 5:26 ` David Miller
2015-08-30 22:54 ` [PATCH net] netlink: rx mmap: fix POLLIN condition Ken-ichirou MATSUZAWA
2015-08-31 4:56 ` David Miller
2015-08-20 7:07 ` [PATCH net] netlink: mmap: fix status setting in skb destructor Ken-ichirou MATSUZAWA
2015-08-26 3:22 ` David Miller
2015-08-28 7:37 ` Ken-ichirou MATSUZAWA
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