Re: [PATCH] fs/ntfs3: Fix integer overflow in ni_fiemap with fiemap_prep()

[Konstantin Komarov]

On 25.08.2021 21:24, Kari Argillander wrote:
> Use fiemap_prep() to check valid flags. It also shrink request scope
> (@len) to what the fs can actually handle.
> 
> This address following Smatch static checker warning:
> 	fs/ntfs3/frecord.c:1894 ni_fiemap()
> 	warn: potential integer overflow from user 'vbo + len'
> 
> Because fiemap_prep() shrinks @len this cannot happened anymore.
> 
> Reported-by Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Link: lore.kernel.org/ntfs3/20210825080440.GA17407@kili/
> 
> Fixes: 4342306f0f0d ("fs/ntfs3: Add file operations and implementation")
> Signed-off-by: Kari Argillander <kari.argillander@xxxxxxxxx>
> ---
>  fs/ntfs3/file.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
> index 59344985c2e8..cb736701f2cc 100644
> --- a/fs/ntfs3/file.c
> +++ b/fs/ntfs3/file.c
> @@ -1210,8 +1210,9 @@ int ntfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>  	int err;
>  	struct ntfs_inode *ni = ntfs_i(inode);
>  
> -	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR)
> -		return -EOPNOTSUPP;
> +	err = fiemap_prep(inode, fieinfo, start, &len, ~FIEMAP_FLAG_XATTR);
> +	if (err)
> +		return err;
>  
>  	ni_lock(ni);
>  
> 

Hello, Dan, Kari!

Thanks for finding and fixing this issue. Applied patch.