Subject: Re: [PATCH] net/802: use struct_size over open coded arithmetic

From: kernel test robot <[email-masked]>
Date: Fri, 28 Jan 2022 20:51:12 +0800

Hi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]
[also build test ERROR on net/master horms-ipvs/master linus/master v5.17-rc1 next-20220128]
[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/cgel-zte-gmail-com/net-802-use-struct_size-over-open-coded-arithmetic/20220128-160925
base:   https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 72d044e4bfa6bd9096536e2e1c62aecfe1a525e4
config: x86_64-randconfig-a015 (https://download.01.org/0day-ci/archive/20220128/[email-masked]/config)
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/9b64e5078d3d779fc56432d43129479f63996c74
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review cgel-zte-gmail-com/net-802-use-struct_size-over-open-coded-arithmetic/20220128-160925
        git checkout 9b64e5078d3d779fc56432d43129479f63996c74
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email-masked]>

All errors (new ones prefixed by >>):

   In file included from include/linux/mm.h:30,
                    from arch/x86/include/asm/cacheflush.h:5,
                    from include/linux/cacheflush.h:5,
                    from include/linux/highmem.h:8,
                    from include/linux/bvec.h:10,
                    from include/linux/skbuff.h:17,
                    from net/802/mrp.c:12:
   net/802/mrp.c: In function 'mrp_attr_create':
>> include/linux/overflow.h:194:18: error: invalid type argument of '->' (have 'struct mrp_attr')
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                  ^~
   net/802/mrp.c:276:17: note: in expansion of macro 'struct_size'
     276 |  attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
         |                 ^~~~~~~~~~~
   In file included from include/linux/container_of.h:5,
                    from include/linux/kernel.h:21,
                    from net/802/mrp.c:10:
   include/linux/overflow.h:194:49: error: invalid type argument of '->' (have 'struct mrp_attr')
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                                                 ^~
   include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
      16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
         |                                                              ^
   include/linux/compiler.h:258:46: note: in expansion of macro '__same_type'
     258 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
         |                                              ^~~~~~~~~~~
   include/linux/overflow.h:194:30: note: in expansion of macro '__must_be_array'
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                              ^~~~~~~~~~~~~~~
   net/802/mrp.c:276:17: note: in expansion of macro 'struct_size'
     276 |  attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
         |                 ^~~~~~~~~~~
   include/linux/overflow.h:194:49: error: invalid type argument of '->' (have 'struct mrp_attr')
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                                                 ^~
   include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
      16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
         |                                                              ^
   include/linux/compiler.h:258:46: note: in expansion of macro '__same_type'
     258 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
         |                                              ^~~~~~~~~~~
   include/linux/overflow.h:194:30: note: in expansion of macro '__must_be_array'
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                              ^~~~~~~~~~~~~~~
   net/802/mrp.c:276:17: note: in expansion of macro 'struct_size'
     276 |  attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
         |                 ^~~~~~~~~~~
   include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
      16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
         |                                                   ^
   include/linux/compiler.h:258:28: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
     258 | #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
         |                            ^~~~~~~~~~~~~~~~~
   include/linux/overflow.h:194:30: note: in expansion of macro '__must_be_array'
     194 |       sizeof(*(p)->member) + __must_be_array((p)->member),\
         |                              ^~~~~~~~~~~~~~~
   net/802/mrp.c:276:17: note: in expansion of macro 'struct_size'
     276 |  attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
         |                 ^~~~~~~~~~~
   In file included from include/linux/mm.h:30,
                    from arch/x86/include/asm/cacheflush.h:5,
                    from include/linux/cacheflush.h:5,
                    from include/linux/highmem.h:8,
                    from include/linux/bvec.h:10,
                    from include/linux/skbuff.h:17,
                    from net/802/mrp.c:12:
>> include/linux/overflow.h:195:14: error: invalid type argument of unary '*' (have 'struct mrp_attr')
     195 |       sizeof(*(p)))
         |              ^~~~
   net/802/mrp.c:276:17: note: in expansion of macro 'struct_size'
     276 |  attr = kmalloc(struct_size(*attr, value, len), GFP_ATOMIC);
         |                 ^~~~~~~~~~~

vim +194 include/linux/overflow.h

610b15c50e86eb Kees Cook           2018-05-07  180  
610b15c50e86eb Kees Cook           2018-05-07  181  /**
610b15c50e86eb Kees Cook           2018-05-07  182   * struct_size() - Calculate size of structure with trailing array.
610b15c50e86eb Kees Cook           2018-05-07  183   * @p: Pointer to the structure.
610b15c50e86eb Kees Cook           2018-05-07  184   * @member: Name of the array member.
b19d57d0f3cc6f Gustavo A. R. Silva 2020-06-08  185   * @count: Number of elements in the array.
610b15c50e86eb Kees Cook           2018-05-07  186   *
610b15c50e86eb Kees Cook           2018-05-07  187   * Calculates size of memory needed for structure @p followed by an
b19d57d0f3cc6f Gustavo A. R. Silva 2020-06-08  188   * array of @count number of @member elements.
610b15c50e86eb Kees Cook           2018-05-07  189   *
610b15c50e86eb Kees Cook           2018-05-07  190   * Return: number of bytes needed or SIZE_MAX on overflow.
610b15c50e86eb Kees Cook           2018-05-07  191   */
b19d57d0f3cc6f Gustavo A. R. Silva 2020-06-08  192  #define struct_size(p, member, count)					\
b19d57d0f3cc6f Gustavo A. R. Silva 2020-06-08  193  	__ab_c_size(count,						\
610b15c50e86eb Kees Cook           2018-05-07 @194  		    sizeof(*(p)->member) + __must_be_array((p)->member),\
610b15c50e86eb Kees Cook           2018-05-07 @195  		    sizeof(*(p)))
610b15c50e86eb Kees Cook           2018-05-07  196  

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