Re: [linux-next:master 1304/1443] fs/jfs/jfs_dmap.c:196:23: warning: result of comparison of constant 8796093022201 with expression of type 'int' is always false

[Dongliang Mu <mudongliangabcd@gmail.com>]

On Tue, Oct 18, 2022 at 1:50 PM kernel test robot <lkp@intel.com> wrote:
>
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   4ca786ae6681b90b0ec3f4c55c89d12f835f8944
> commit: 920f4b7e923b35fd9d117fd3cb616b310cd41010 [1304/1443] fs: jfs: fix shift-out-of-bounds in dbAllocAG
> config: mips-randconfig-r005-20221017
> compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 791a7ae1ba3efd6bca96338e10ffde557ba83920)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install mips cross compiling tool for clang build
>         # apt-get install binutils-mipsel-linux-gnu
>         # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=920f4b7e923b35fd9d117fd3cb616b310cd41010
>         git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>         git fetch --no-tags linux-next master
>         git checkout 920f4b7e923b35fd9d117fd3cb616b310cd41010
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash fs/jfs/
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> fs/jfs/jfs_dmap.c:196:23: warning: result of comparison of constant 8796093022201 with expression of type 'int' is always false [-Wtautological-constant-out-of-range-compare]
>            if (bmp->db_agl2size > MAXMAPSIZE - L2MAXAG) {
>                ~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~
>    1 warning generated.

Hi Dave,

I did not double check the upper bound of db_agl2size. It seems the
upper bound should be L2MAXL2SIZE - L2MAXAG, other than MAXMAPSIZE -
L2MAXAG.

And L2MAXL2SIZE = L2BPERDMAP + 3 * L2LPERCTL = 13+3*10 = 43.

I will send a fixes commit.

>
>
> vim +/int +196 fs/jfs/jfs_dmap.c
>
>    135
>    136  /*
>    137   * NAME:        dbMount()
>    138   *
>    139   * FUNCTION:    initializate the block allocation map.
>    140   *
>    141   *              memory is allocated for the in-core bmap descriptor and
>    142   *              the in-core descriptor is initialized from disk.
>    143   *
>    144   * PARAMETERS:
>    145   *      ipbmap  - pointer to in-core inode for the block map.
>    146   *
>    147   * RETURN VALUES:
>    148   *      0       - success
>    149   *      -ENOMEM - insufficient memory
>    150   *      -EIO    - i/o error
>    151   *      -EINVAL - wrong bmap data
>    152   */
>    153  int dbMount(struct inode *ipbmap)
>    154  {
>    155          struct bmap *bmp;
>    156          struct dbmap_disk *dbmp_le;
>    157          struct metapage *mp;
>    158          int i, err;
>    159
>    160          /*
>    161           * allocate/initialize the in-memory bmap descriptor
>    162           */
>    163          /* allocate memory for the in-memory bmap descriptor */
>    164          bmp = kmalloc(sizeof(struct bmap), GFP_KERNEL);
>    165          if (bmp == NULL)
>    166                  return -ENOMEM;
>    167
>    168          /* read the on-disk bmap descriptor. */
>    169          mp = read_metapage(ipbmap,
>    170                             BMAPBLKNO << JFS_SBI(ipbmap->i_sb)->l2nbperpage,
>    171                             PSIZE, 0);
>    172          if (mp == NULL) {
>    173                  err = -EIO;
>    174                  goto err_kfree_bmp;
>    175          }
>    176
>    177          /* copy the on-disk bmap descriptor to its in-memory version. */
>    178          dbmp_le = (struct dbmap_disk *) mp->data;
>    179          bmp->db_mapsize = le64_to_cpu(dbmp_le->dn_mapsize);
>    180          bmp->db_nfree = le64_to_cpu(dbmp_le->dn_nfree);
>    181          bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage);
>    182          bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag);
>    183          if (!bmp->db_numag) {
>    184                  err = -EINVAL;
>    185                  goto err_release_metapage;
>    186          }
>    187
>    188          bmp->db_maxlevel = le32_to_cpu(dbmp_le->dn_maxlevel);
>    189          bmp->db_maxag = le32_to_cpu(dbmp_le->dn_maxag);
>    190          bmp->db_agpref = le32_to_cpu(dbmp_le->dn_agpref);
>    191          bmp->db_aglevel = le32_to_cpu(dbmp_le->dn_aglevel);
>    192          bmp->db_agheight = le32_to_cpu(dbmp_le->dn_agheight);
>    193          bmp->db_agwidth = le32_to_cpu(dbmp_le->dn_agwidth);
>    194          bmp->db_agstart = le32_to_cpu(dbmp_le->dn_agstart);
>    195          bmp->db_agl2size = le32_to_cpu(dbmp_le->dn_agl2size);
>  > 196          if (bmp->db_agl2size > MAXMAPSIZE - L2MAXAG) {
>    197                  err = -EINVAL;
>    198                  goto err_release_metapage;
>    199          }
>    200
>    201          for (i = 0; i < MAXAG; i++)
>    202                  bmp->db_agfree[i] = le64_to_cpu(dbmp_le->dn_agfree[i]);
>    203          bmp->db_agsize = le64_to_cpu(dbmp_le->dn_agsize);
>    204          bmp->db_maxfreebud = dbmp_le->dn_maxfreebud;
>    205
>    206          /* release the buffer. */
>    207          release_metapage(mp);
>    208
>    209          /* bind the bmap inode and the bmap descriptor to each other. */
>    210          bmp->db_ipbmap = ipbmap;
>    211          JFS_SBI(ipbmap->i_sb)->bmap = bmp;
>    212
>    213          memset(bmp->db_active, 0, sizeof(bmp->db_active));
>    214
>    215          /*
>    216           * allocate/initialize the bmap lock
>    217           */
>    218          BMAP_LOCK_INIT(bmp);
>    219
>    220          return (0);
>    221
>    222  err_release_metapage:
>    223          release_metapage(mp);
>    224  err_kfree_bmp:
>    225          kfree(bmp);
>    226          return err;
>    227  }
>    228
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp