[bug report] fs/ntfs3: Rework file operations

[bug report] fs/ntfs3: Rework file operations

[Dan Carpenter]

Hello Konstantin Komarov,

This is a semi-automatic email about new static checker warnings.

The patch 78ab59fee07f: "fs/ntfs3: Rework file operations" from Aug
31, 2021, leads to the following Smatch complaint:

    fs/ntfs3/frecord.c:2887 ni_remove_name_undo()
    error: we previously assumed 'de2' could be null (see line 2876)

fs/ntfs3/frecord.c
  2871  bool ni_remove_name_undo(struct ntfs_inode *dir_ni, struct ntfs_inode *ni,
  2872                           struct NTFS_DE *de, struct NTFS_DE *de2, int undo_step)
  2873  {
  2874          struct ntfs_sb_info *sbi = ni->mi.sbi;
  2875          struct ATTRIB *attr;
  2876          u16 de_key_size = de2 ? le16_to_cpu(de2->key_size) : 0;
                                  ^^^
This assumes "de2" can be NULL.

  2877  
  2878          switch (undo_step) {
  2879          case 4:
  2880                  if (ni_insert_resident(ni, de_key_size, ATTR_NAME, NULL, 0,
  2881                                         &attr, NULL, NULL)) {
  2882                          return false;
  2883                  }
  2884                  memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), de2 + 1, de_key_size);
  2885  
  2886                  mi_get_ref(&ni->mi, &de2->ref);
                                            ^^^^^^^^^
Unchecked dereference.

  2887                  de2->size = cpu_to_le16(ALIGN(de_key_size, 8) +
  2888                                          sizeof(struct NTFS_DE));
  2889                  de2->flags = 0;
  2890                  de2->res = 0;
  2891  
  2892                  if (indx_insert_entry(&dir_ni->dir, dir_ni, de2, sbi, NULL,
  2893                                        1)) {
  2894                          return false;
  2895                  }
  2896                  fallthrough;
  2897  
  2898          case 2:
  2899                  de_key_size = le16_to_cpu(de->key_size);

No need for this assignment.

  2900  
  2901                  if (ni_insert_resident(ni, de_key_size, ATTR_NAME, NULL, 0,
  2902                                         &attr, NULL, NULL)) {
  2903                          return false;
  2904                  }
  2905  
  2906                  memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), de + 1, de_key_size);
  2907                  mi_get_ref(&ni->mi, &de->ref);
  2908  
  2909                  if (indx_insert_entry(&dir_ni->dir, dir_ni, de, sbi, NULL, 1)) {
  2910                          return false;
  2911                  }
  2912          }

regards,
dan carpenter