[v10,0/7] Introduce sendpage_ok() to detect misused sendpage in network related drivers

As Sagi Grimberg suggested, the original fix is refind to a more common
inline routine:
    static inline bool sendpage_ok(struct page *page)
    {
        return  (!PageSlab(page) && page_count(page) >= 1);
    }
If sendpage_ok() returns true, the checking page can be handled by the
concrete zero-copy sendpage method in network layer.

The v10 series has 7 patches, fixes a WARN_ONCE() usage from v9 series,
- The 1st patch in this series introduces sendpage_ok() in header file
  include/linux/net.h.
- The 2nd patch adds WARN_ONCE() for improper zero-copy send in
  kernel_sendpage().
- The 3rd patch fixes the page checking issue in nvme-over-tcp driver.
- The 4th patch adds page_count check by using sendpage_ok() in
  do_tcp_sendpages() as Eric Dumazet suggested.
- The 5th and 6th patches just replace existing open coded checks with
  the inline sendpage_ok() routine.

Coly Li

Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Chris Leech <cleech@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <amwang@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jan Kara <jack@suse.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lee Duncan <lduncan@suse.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Mikhail Skorzhinskii <mskorzhinskiy@solarflare.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: Vlastimil Babka <vbabka@suse.com>
---
Changelog:
v10, fix WARN_ONCE() usage, and add Reivewed-by tag from Lee Duncan.
v9, fix a typo pointed out by Greg KH.
    add Acked-by tags from Martin K. Petersen and Ilya Dryomov.
v8: add WARN_ONCE() in kernel_sendpage() as Christoph suggested.
v7: remove outer brackets from the return line of sendpage_ok() as
    Eric Dumazet suggested.
v6: fix page check in do_tcp_sendpages(), as Eric Dumazet suggested.
    replace other open coded checks with sendpage_ok() in libceph,
    iscsi drivers.
v5, include linux/mm.h in include/linux/net.h
v4, change sendpage_ok() as an inline helper, and post it as
    separate patch, as Christoph Hellwig suggested.
v3, introduce a more common sendpage_ok() as Sagi Grimberg suggested.
v2, fix typo in patch subject
v1, the initial version. 

Coly Li (7):
  net: introduce helper sendpage_ok() in include/linux/net.h
  net: add WARN_ONCE in kernel_sendpage() for improper zero-copy send
  nvme-tcp: check page by sendpage_ok() before calling kernel_sendpage()
  tcp: use sendpage_ok() to detect misused .sendpage
  drbd: code cleanup by using sendpage_ok() to check page for
    kernel_sendpage()
  scsi: libiscsi: use sendpage_ok() in iscsi_tcp_segment_map()
  libceph: use sendpage_ok() in ceph_tcp_sendpage()

 drivers/block/drbd/drbd_main.c |  2 +-
 drivers/nvme/host/tcp.c        |  7 +++----
 drivers/scsi/libiscsi_tcp.c    |  2 +-
 include/linux/net.h            | 16 ++++++++++++++++
 net/ceph/messenger.c           |  2 +-
 net/ipv4/tcp.c                 |  3 ++-
 net/socket.c                   |  6 ++++--
 7 files changed, 28 insertions(+), 10 deletions(-)

From: Coly Li <colyli@suse.de>
Date: Fri,  2 Oct 2020 16:27:27 +0800

> As Sagi Grimberg suggested, the original fix is refind to a more common
> inline routine:
>     static inline bool sendpage_ok(struct page *page)
>     {
>         return  (!PageSlab(page) && page_count(page) >= 1);
>     }
> If sendpage_ok() returns true, the checking page can be handled by the
> concrete zero-copy sendpage method in network layer.

Series applied.

> The v10 series has 7 patches, fixes a WARN_ONCE() usage from v9 series,
 ...

I still haven't heard from you how such a fundamental build failure
was even possible.

If the v9 patch series did not even compile, how in the world did you
perform functional testing of these changes?

Please explain this to me, instead of just quietly fixing it and
posting an updated series.

Thank you.

On 2020/10/3 06:28, David Miller wrote:
> From: Coly Li <colyli@suse.de>
> Date: Fri,  2 Oct 2020 16:27:27 +0800
> 
>> As Sagi Grimberg suggested, the original fix is refind to a more common
>> inline routine:
>>     static inline bool sendpage_ok(struct page *page)
>>     {
>>         return  (!PageSlab(page) && page_count(page) >= 1);
>>     }
>> If sendpage_ok() returns true, the checking page can be handled by the
>> concrete zero-copy sendpage method in network layer.
> 
> Series applied.
> 
>> The v10 series has 7 patches, fixes a WARN_ONCE() usage from v9 series,
>  ...
> 
> I still haven't heard from you how such a fundamental build failure
> was even possible.
> 

Hi David,

Here is the detail steps how I leaked this uncompleted patch to you,
1) Add WARN_ONCE() as WARN_ON() to kernel_sendpage(). Maybe I was still
hesitating when I typed WARN_ONCE() on keyboard.
2) Generate the patches, prepare to post
3) Hmm, compiling failed, oh it is WARN_ONCE(). Yeah, WARN_ONCE() might
be more informative and better.
4) Modify to use WARN_ONCE() and compile and try, looks fine.
5) Re-generate the patches to overwrite the previous ones.
6) Post the patches.

The missing part was, before I post the patches, I should do rebase and
commit the change, but (interrupted by other stuffs) it skipped in my
mind. Although I regenerated the series but the change was not included.
The result was, uncompleted patch posted and the second-half change
still stayed in my local file.


> If the v9 patch series did not even compile, how in the world did you
> perform functional testing of these changes?
> 

Only 0002-net-add-WARN_ONCE-in-kernel_sendpage-for-improper-ze.patch was
tested in v9 series, other tests were done in previous versions.

> Please explain this to me, instead of just quietly fixing it and
> posting an updated series.


And not all the patches in the series were tested. Here is the testing
coverage of the series:

The following ones were tested and verified to break nothing and avoid
the mm corruption and panic,
0001-net-introduce-helper-sendpage_ok-in-include-linux-ne.patch
0002-net-add-WARN_ONCE-in-kernel_sendpage-for-improper-ze.patch
0003-nvme-tcp-check-page-by-sendpage_ok-before-calling-ke.patch
0006-scsi-libiscsi-use-sendpage_ok-in-iscsi_tcp_segment_m.patch

The following ones were not tested, due to complicated environment setup,
0005-drbd-code-cleanup-by-using-sendpage_ok-to-check-page.patch
0007-libceph-use-sendpage_ok-in-ceph_tcp_sendpage.patch

This patch I didn't explicitly test, due to lack of knowledge to modify
network code to trigger a buggy condition. It just went with other
tested patches,
0004-tcp-use-sendpage_ok-to-detect-misused-.sendpage.patch


Back to the built failure, I don't have excuse for leaking this
uncompleted version to you. Of cause I will try to avoid to
inefficiently occupy maintainer's time by such silly mess up.

Thanks for your review and the thorough maintenance.

Coly Li