clean-up-ext4_xattr_inode_get

   1 ext4: clean up ext4_xattr_inode_get()
   2
   3 From: Tahsin Erdogan <tahsin@google.com>
   4
   5 The input and output values of *size parameter are equal on successful
   6 return from ext4_xattr_inode_get().  On error return, the callers ignore
   7 the output value so there is no need to update it.
   8
   9 Also check for NULL return from ext4_bread().  If the actual xattr inode
  10 size happens to be smaller than the expected size, ext4_bread() may
  11 return NULL which would indicate data corruption.
  12
  13 Signed-off-by: Tahsin Erdogan <tahsin@google.com>
  14 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  15 ---
  16  fs/ext4/xattr.c | 35 +++++++++++++----------------------
  17  1 file changed, 13 insertions(+), 22 deletions(-)
  18
  19 diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
  20 index d9477d01be9b..8e855fc2eb03 100644
  21 --- a/fs/ext4/xattr.c
  22 +++ b/fs/ext4/xattr.c
  23 @@ -278,37 +278,28 @@ ext4_xattr_find_entry(struct ext4_xattr_entry **pentry, int name_index,
  24  /*
  25   * Read the EA value from an inode.
  26   */
  27 -static int
  28 -ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t *size)
  29 +static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
  30  {
  31         unsigned long block = 0;
  32         struct buffer_head *bh = NULL;
  33 -       int blocksize;
  34 -       size_t csize, ret_size = 0;
  35 -
  36 -       if (*size == 0)
  37 -               return 0;
  38 +       int blocksize = ea_inode->i_sb->s_blocksize;
  39 +       size_t csize, copied = 0;
  40
  41 -       blocksize = ea_inode->i_sb->s_blocksize;
  42 -
  43 -       while (ret_size < *size) {
  44 -               csize = (*size - ret_size) > blocksize ? blocksize :
  45 -                                                       *size - ret_size;
  46 +       while (copied < size) {
  47 +               csize = (size - copied) > blocksize ? blocksize : size - copied;
  48                 bh = ext4_bread(NULL, ea_inode, block, 0);
  49 -               if (IS_ERR(bh)) {
  50 -                       *size = ret_size;
  51 +               if (IS_ERR(bh))
  52                         return PTR_ERR(bh);
  53 -               }
  54 +               if (!bh)
  55 +                       return -EFSCORRUPTED;
  56 +
  57                 memcpy(buf, bh->b_data, csize);
  58                 brelse(bh);
  59
  60                 buf += csize;
  61                 block += 1;
  62 -               ret_size += csize;
  63 +               copied += csize;
  64         }
  65 -
  66 -       *size = ret_size;
  67 -
  68         return 0;
  69  }
  70
  71 @@ -360,7 +351,7 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
  72   */
  73  static int
  74  ext4_xattr_inode_get(struct inode *inode, unsigned long ea_ino, void *buffer,
  75 -                    size_t *size)
  76 +                    size_t size)
  77  {
  78         struct inode *ea_inode;
  79         int ret;
  80 @@ -417,7 +408,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
  81                 if (entry->e_value_inum) {
  82                         error = ext4_xattr_inode_get(inode,
  83                                              le32_to_cpu(entry->e_value_inum),
  84 -                                            buffer, &size);
  85 +                                            buffer, size);
  86                         if (error)
  87                                 goto cleanup;
  88                 } else {
  89 @@ -467,7 +458,7 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
  90                 if (entry->e_value_inum) {
  91                         error = ext4_xattr_inode_get(inode,
  92                                              le32_to_cpu(entry->e_value_inum),
  93 -                                            buffer, &size);
  94 +                                            buffer, size);
  95                         if (error)
  96                                 goto cleanup;
  97                 } else {
  98 --
  99 2.13.1.611.g7e3b11ae1-goog
 100
 101