Re: [PATCH net] net: hns3: fix strscpy causing content truncation issue

[Jijie Shao]

on 2023/8/9 15:03, Leon Romanovsky wrote:
> On Wed, Aug 09, 2023 at 10:09:02AM +0800, Jijie Shao wrote:
> > From: Hao Chen <chenhao418@xxxxxxxxxx>
> >
> > hns3_dbg_fill_content()/hclge_dbg_fill_content() is aim to integrate some
> > items to a string for content, and we add '\n' and '\0' in the last
> > two bytes of content.
> >
> > strscpy() will add '\0' in the last byte of destination buffer(one of
> > items), it result in finishing content print ahead of schedule and some
> > dump content truncation.
> >
> > One Error log shows as below:
> > cat mac_list/uc
> > UC MAC_LIST:
> >
> > Expected:
> > UC MAC_LIST:
> > FUNC_ID  MAC_ADDR            STATE
> > pf       00:2b:19:05:03:00   ACTIVE
> >
> > The destination buffer is length-bounded and not required to be
> > NUL-terminated, so just change strscpy() to memcpy() to fix it.
> I think that you should change to strtomem() and not use plain memcpy().
>
> Thanks

Hi:

We tried to replace memcpy with strtomem, but errors was reported during 
compilation:
/kernel/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c: In 
function ‘hclge_dbg_fill_content.part.0’:
/kernel/include/linux/compiler_types.h:397:38: error: call to 
‘__compiletime_assert_519’ declared with attribute error: BUILD_BUG_ON 
failed: !__builtin_constant_p(_dest_len) || _dest_len == (size_t)-1
  397 |  _compiletime_assert(condition, msg, __compiletime_assert_, 
__COUNTER__)
      |                                      ^
/kernel/include/linux/compiler_types.h:378:4: note: in definition of 
macro ‘__compiletime_assert’
  378 |    prefix ## suffix();    \
      |    ^~~~~~
/kernel/include/linux/compiler_types.h:397:2: note: in expansion of 
macro ‘_compiletime_assert’
  397 |  _compiletime_assert(condition, msg, __compiletime_assert_, 
__COUNTER__)
      |  ^~~~~~~~~~~~~~~~~~~
/kernel/include/linux/build_bug.h:39:37: note: in expansion of macro 
‘compiletime_assert’
   39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), 
msg)
      |                                     ^~~~~~~~~~~~~~~~~~
/kernel/include/linux/build_bug.h:50:2: note: in expansion of macro 
‘BUILD_BUG_ON_MSG’
   50 |  BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
      |  ^~~~~~~~~~~~~~~~
/kernel/include/linux/string.h:302:2: note: in expansion of macro 
‘BUILD_BUG_ON’
  302 |  BUILD_BUG_ON(!__builtin_constant_p(_dest_len) ||  \
      |  ^~~~~~~~~~~~
/kernel/drivers/net/ethernet/hisilicon/hns3/hns3pf/hclge_debugfs.c:115:4: 
note: in expansion of macro ‘strtomem’
  115 |    strtomem(pos, result[i]);
      |    ^~~~~~~~

In the strtomem macro, __builtin_object_size is used to calculate the 
_dest_len.
We tried to print the _dest_len directly, and the result was -1.
How can we solve this?

Regards
Jijie Shao