Re: [PATCH v2 3/5] uaccess-buffer: add CONFIG_GENERIC_ENTRY support

Tuesday, 23 November 2021

Hi Peter,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/sched/core]
[also build test WARNING on bpf-next/master bpf/master linus/master v5.16-rc2]
[cannot apply to arm64/for-next/core arm-perf/for-next/perf tip/core/entry next-20211123]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:   
https://github.com/0day-ci/linux/commits/Peter-Collingbourne/kernel-intro...
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
cb0e52b7748737b2cf6481fdd9b920ce7e1ebbdf
config: i386-tinyconfig
(https://download.01.org/0day-ci/archive/20211123/202111231840.JTkqlqKw-lk...)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        #
https://github.com/0day-ci/linux/commit/7cd6f102201f3ea35eea1b990f7543e89...
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review
Peter-Collingbourne/kernel-introduce-uaccess-logging/20211123-131922
        git checkout 7cd6f102201f3ea35eea1b990f7543e890b7fdbb
        # save the config file to linux build tree
        make W=1 ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp(a)intel.com&gt;

All warnings (new ones prefixed by >>):

   kernel/uaccess-buffer.c: In function '__uaccess_buffer_syscall_entry':
...
> kernel/uaccess-buffer.c:105:16: warning: cast to pointer from
integer of different size [-Wint-to-pointer-cast]      105 |  buf->ubegin =
(struct uaccess_buffer_entry __user *)desc.addr;
         |                ^
   kernel/uaccess-buffer.c: In function '__uaccess_buffer_syscall_exit':
...
> kernel/uaccess-buffer.c:117:14: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]      117 |  desc.addr =
(u64)(buf->ubegin + num_entries);
         |              ^
...
> kernel/uaccess-buffer.c:122:9: warning: ignoring return value of
'copy_to_user', declared with attribute warn_unused_result [-Wunused-result]
     122 |   (void)copy_to_user(buf->desc_ptr, &desc, sizeof(desc));
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +105 kernel/uaccess-buffer.c

e050ed271bb000 Peter Collingbourne 2021-11-22   87  
e050ed271bb000 Peter Collingbourne 2021-11-22   88  void
__uaccess_buffer_syscall_entry(void)
e050ed271bb000 Peter Collingbourne 2021-11-22   89  {
e050ed271bb000 Peter Collingbourne 2021-11-22   90  	struct uaccess_buffer_info *buf =
&current->uaccess_buffer;
e050ed271bb000 Peter Collingbourne 2021-11-22   91  	struct uaccess_descriptor desc;
e050ed271bb000 Peter Collingbourne 2021-11-22   92  
e050ed271bb000 Peter Collingbourne 2021-11-22   93  	if (get_user(buf->desc_ptr,
buf->desc_ptr_ptr) || !buf->desc_ptr ||
e050ed271bb000 Peter Collingbourne 2021-11-22   94  	    put_user(0, buf->desc_ptr_ptr)
||
e050ed271bb000 Peter Collingbourne 2021-11-22   95  	    copy_from_user(&desc,
buf->desc_ptr, sizeof(desc)))
e050ed271bb000 Peter Collingbourne 2021-11-22   96  		return;
e050ed271bb000 Peter Collingbourne 2021-11-22   97  
e050ed271bb000 Peter Collingbourne 2021-11-22   98  	if (desc.size > 1024)
e050ed271bb000 Peter Collingbourne 2021-11-22   99  		desc.size = 1024;
e050ed271bb000 Peter Collingbourne 2021-11-22  100  
e050ed271bb000 Peter Collingbourne 2021-11-22  101  	buf->kbegin = kmalloc_array(
e050ed271bb000 Peter Collingbourne 2021-11-22  102  		desc.size, sizeof(struct
uaccess_buffer_entry), GFP_KERNEL);
e050ed271bb000 Peter Collingbourne 2021-11-22  103  	buf->kcur = buf->kbegin;
e050ed271bb000 Peter Collingbourne 2021-11-22  104  	buf->kend = buf->kbegin +
desc.size;
e050ed271bb000 Peter Collingbourne 2021-11-22 @105  	buf->ubegin = (struct
uaccess_buffer_entry __user *)desc.addr;
e050ed271bb000 Peter Collingbourne 2021-11-22  106  }
e050ed271bb000 Peter Collingbourne 2021-11-22  107  
e050ed271bb000 Peter Collingbourne 2021-11-22  108  void
__uaccess_buffer_syscall_exit(void)
e050ed271bb000 Peter Collingbourne 2021-11-22  109  {
e050ed271bb000 Peter Collingbourne 2021-11-22  110  	struct uaccess_buffer_info *buf =
&current->uaccess_buffer;
e050ed271bb000 Peter Collingbourne 2021-11-22  111  	u64 num_entries = buf->kcur -
buf->kbegin;
e050ed271bb000 Peter Collingbourne 2021-11-22  112  	struct uaccess_descriptor desc;
e050ed271bb000 Peter Collingbourne 2021-11-22  113  
e050ed271bb000 Peter Collingbourne 2021-11-22  114  	if (!buf->kcur)
e050ed271bb000 Peter Collingbourne 2021-11-22  115  		return;
e050ed271bb000 Peter Collingbourne 2021-11-22  116  
e050ed271bb000 Peter Collingbourne 2021-11-22 @117  	desc.addr = (u64)(buf->ubegin +
num_entries);
e050ed271bb000 Peter Collingbourne 2021-11-22  118  	desc.size = buf->kend -
buf->kcur;
e050ed271bb000 Peter Collingbourne 2021-11-22  119  	buf->kcur = 0;
e050ed271bb000 Peter Collingbourne 2021-11-22  120  	if (copy_to_user(buf->ubegin,
buf->kbegin,
e050ed271bb000 Peter Collingbourne 2021-11-22  121  			 num_entries * sizeof(struct
uaccess_buffer_entry)) == 0)
e050ed271bb000 Peter Collingbourne 2021-11-22 @122  		(void)copy_to_user(buf->desc_ptr,
&desc, sizeof(desc));

---
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