On Mon,  6 Nov 2023 19:01:41 +0800
Ferry Meng <[email protected]> wrote:

> After commit 1c7f49a76773 ("erofs: tidy up EROFS on-disk naming"),
> there is a unique `union erofs_inode_i_u` so that we could parse
> the union directly.
> 
> Besides, it also replaces `inode->i_sb` with `sb` for simplicity.
> 
> Signed-off-by: Ferry Meng <[email protected]>
> ---
>  fs/erofs/inode.c | 98 +++++++++++++++++-------------------------------
>  1 file changed, 35 insertions(+), 63 deletions(-)
> 
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index edc8ec7581b8..99535c8c53b5 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -15,11 +15,11 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>       struct erofs_sb_info *sbi = EROFS_SB(sb);
>       struct erofs_inode *vi = EROFS_I(inode);
>       const erofs_off_t inode_loc = erofs_iloc(inode);
> -
>       erofs_blk_t blkaddr, nblks = 0;
>       void *kaddr;
>       struct erofs_inode_compact *dic;
>       struct erofs_inode_extended *die, *copied = NULL;
> +     union erofs_inode_i_u *iu;
>       unsigned int ifmt;
>       int err;
>  
> @@ -35,9 +35,8 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>  
>       dic = kaddr + *ofs;
>       ifmt = le16_to_cpu(dic->i_format);
> -
>       if (ifmt & ~EROFS_I_ALL) {
> -             erofs_err(inode->i_sb, "unsupported i_format %u of nid %llu",
> +             erofs_err(sb, "unsupported i_format %u of nid %llu",
>                         ifmt, vi->nid);
>               err = -EOPNOTSUPP;
>               goto err_out;
> @@ -45,7 +44,7 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>  
>       vi->datalayout = erofs_inode_datalayout(ifmt);
>       if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
> -             erofs_err(inode->i_sb, "unsupported datalayout %u of nid %llu",
> +             erofs_err(sb, "unsupported datalayout %u of nid %llu",
>                         vi->datalayout, vi->nid);
>               err = -EOPNOTSUPP;
>               goto err_out;
> @@ -82,40 +81,15 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>               vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
>  
>               inode->i_mode = le16_to_cpu(die->i_mode);
> -             switch (inode->i_mode & S_IFMT) {
> -             case S_IFREG:
> -             case S_IFDIR:
> -             case S_IFLNK:
> -                     vi->raw_blkaddr = le32_to_cpu(die->i_u.raw_blkaddr);
> -                     break;
> -             case S_IFCHR:
> -             case S_IFBLK:
> -                     inode->i_rdev =
> -                             new_decode_dev(le32_to_cpu(die->i_u.rdev));
> -                     break;
> -             case S_IFIFO:
> -             case S_IFSOCK:
> -                     inode->i_rdev = 0;
> -                     break;
> -             default:
> -                     goto bogusimode;
> -             }
> +             iu = &die->i_u;
>               i_uid_write(inode, le32_to_cpu(die->i_uid));
>               i_gid_write(inode, le32_to_cpu(die->i_gid));
>               set_nlink(inode, le32_to_cpu(die->i_nlink));
> -
> -             /* extended inode has its own timestamp */
> +             /* each extended inode has its own timestamp */
>               inode_set_ctime(inode, le64_to_cpu(die->i_mtime),
>                               le32_to_cpu(die->i_mtime_nsec));
>  
>               inode->i_size = le64_to_cpu(die->i_size);
> -
> -             /* total blocks for compressed files */
> -             if (erofs_inode_is_data_compressed(vi->datalayout))
> -                     nblks = le32_to_cpu(die->i_u.compressed_blocks);
> -             else if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
> -                     /* fill chunked inode summary info */
> -                     vi->chunkformat = le16_to_cpu(die->i_u.c.format);
>               kfree(copied);
>               copied = NULL;
>               break;
> @@ -125,49 +99,51 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>               vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
>  
>               inode->i_mode = le16_to_cpu(dic->i_mode);
> -             switch (inode->i_mode & S_IFMT) {
> -             case S_IFREG:
> -             case S_IFDIR:
> -             case S_IFLNK:
> -                     vi->raw_blkaddr = le32_to_cpu(dic->i_u.raw_blkaddr);
> -                     break;
> -             case S_IFCHR:
> -             case S_IFBLK:
> -                     inode->i_rdev =
> -                             new_decode_dev(le32_to_cpu(dic->i_u.rdev));
> -                     break;
> -             case S_IFIFO:
> -             case S_IFSOCK:
> -                     inode->i_rdev = 0;
> -                     break;
> -             default:
> -                     goto bogusimode;
> -             }
> +             iu = &dic->i_u;
>               i_uid_write(inode, le16_to_cpu(dic->i_uid));
>               i_gid_write(inode, le16_to_cpu(dic->i_gid));
>               set_nlink(inode, le16_to_cpu(dic->i_nlink));
> -
>               /* use build time for compact inodes */
>               inode_set_ctime(inode, sbi->build_time, sbi->build_time_nsec);
>  
>               inode->i_size = le32_to_cpu(dic->i_size);
> -             if (erofs_inode_is_data_compressed(vi->datalayout))
> -                     nblks = le32_to_cpu(dic->i_u.compressed_blocks);
> -             else if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
> -                     vi->chunkformat = le16_to_cpu(dic->i_u.c.format);
>               break;
>       default:
> -             erofs_err(inode->i_sb,
> -                       "unsupported on-disk inode version %u of nid %llu",
> +             erofs_err(sb, "unsupported on-disk inode version %u of nid 
> %llu",
>                         erofs_inode_version(ifmt), vi->nid);
>               err = -EOPNOTSUPP;
>               goto err_out;
>       }
>  
> -     if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
> +     switch (inode->i_mode & S_IFMT) {
> +     case S_IFREG:
> +     case S_IFDIR:
> +     case S_IFLNK:
> +             vi->raw_blkaddr = le32_to_cpu(iu->raw_blkaddr);

may cause use-after-free for acrossing block boundary case due to kfree(copied) 
before?

> +             break;
> +     case S_IFCHR:
> +     case S_IFBLK:
> +             inode->i_rdev = new_decode_dev(le32_to_cpu(iu->rdev));
> +             break;
> +     case S_IFIFO:
> +     case S_IFSOCK:
> +             inode->i_rdev = 0;
> +             break;
> +     default:
> +             erofs_err(sb, "bogus i_mode (%o) @ nid %llu", inode->i_mode,
> +                       vi->nid);
> +             err = -EFSCORRUPTED;
> +             goto err_out;
> +     }
> +
> +     /* total blocks for compressed files */
> +     if (erofs_inode_is_data_compressed(vi->datalayout)) {
> +             nblks = le32_to_cpu(iu->compressed_blocks);
> +     } else if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
> +             /* fill chunked inode summary info */
> +             vi->chunkformat = le16_to_cpu(iu->c.format);
>               if (vi->chunkformat & ~EROFS_CHUNK_FORMAT_ALL) {
> -                     erofs_err(inode->i_sb,
> -                               "unsupported chunk format %x of nid %llu",
> +                     erofs_err(sb, "unsupported chunk format %x of nid %llu",
>                                 vi->chunkformat, vi->nid);
>                       err = -EOPNOTSUPP;
>                       goto err_out;
> @@ -190,10 +166,6 @@ static void *erofs_read_inode(struct erofs_buf *buf,
>               inode->i_blocks = nblks << (sb->s_blocksize_bits - 9);
>       return kaddr;
>  
> -bogusimode:
> -     erofs_err(inode->i_sb, "bogus i_mode (%o) @ nid %llu",
> -               inode->i_mode, vi->nid);
> -     err = -EFSCORRUPTED;
>  err_out:
>       DBG_BUGON(1);
>       kfree(copied);

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