Re: [PATCH] ext4: fix kernel BUG in ext4_write_inline_data_end

[Jan Kara]

On Mon 08-06-26 06:52:27, Aditya Prakash Srivastava wrote:
> When the data=journal mount option is used, the ext4_journalled_write_end()
> function incorrectly calls ext4_write_inline_data_end() without checking
> if the EXT4_STATE_MAY_INLINE_DATA flag is still set on the inode.
> 
> If a previous attempt to convert the inline data to an extent failed (e.g.
> due to ENOSPC), the EXT4_STATE_MAY_INLINE_DATA flag is cleared, but
> the EXT4_INODE_INLINE_DATA flag remains set. In this scenario, the next
> call to ext4_write_begin() will not prepare the inline data xattr for
> writing, but ext4_journalled_write_end() will incorrectly attempt to write
> to it, triggering a BUG_ON(pos + len > EXT4_I(inode)->i_inline_size) in
> ext4_write_inline_data() since i_inline_size was not expanded.
> 
> Fix this by ensuring that ext4_journalled_write_end() only calls
> ext4_write_inline_data_end() if the EXT4_STATE_MAY_INLINE_DATA flag is
> set, mirroring the behavior of ext4_write_end() and ext4_da_write_end().
> 
> Reported-by: syzbot+0c89d865531d053abb2d@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=0c89d865531d053abb2d
> Fixes: 3fdcfb668fd7 ("ext4: add journalled write support for inline data")
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@xxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/inode.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index c2c2d6ac7f3d..4fce9ec176f8 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1560,7 +1560,8 @@ static int ext4_journalled_write_end(const struct kiocb *iocb,
>  
>  	BUG_ON(!ext4_handle_valid(handle));
>  
> -	if (ext4_has_inline_data(inode))
> +	if (ext4_has_inline_data(inode) &&
> +	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))
>  		return ext4_write_inline_data_end(inode, pos, len, copied,
>  						  folio);
>  
> -- 
> 2.47.3
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR