Re: [edk2-platforms][PATCH v3 11/11] Ext4Pkg: Filter out directory entry names containing \0 as invalid

["Marvin Häuser" <mhaeuser@posteo.de>]

On 27. Jan 2023, at 10:29, Savva Mitrofanov <savvamtr@gmail.com> wrote:
> 
> The directory entry name conventions forbid having null-terminator
> symbols in its body and can lead to undefined behavior conditions
> and crashes
> 
> Cc: Marvin Häuser <mhaeuser@posteo.de>
> Cc: Pedro Falcato <pedro.falcato@gmail.com>
> Cc: Vitaly Cheptsov <vit9696@protonmail.com>
> Fixes: 89b2bb0db263 ("Ext4Pkg: Fix and clarify handling regarding non-utf8 dir entries")
> Signed-off-by: Savva Mitrofanov <savvamtr@gmail.com>
> ---
> Features/Ext4Pkg/Ext4Dxe/Directory.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/Features/Ext4Pkg/Ext4Dxe/Directory.c b/Features/Ext4Pkg/Ext4Dxe/Directory.c
> index 0753a20b5377..465749c9b51d 100644
> --- a/Features/Ext4Pkg/Ext4Dxe/Directory.c
> +++ b/Features/Ext4Pkg/Ext4Dxe/Directory.c
> @@ -28,9 +28,16 @@ Ext4GetUcs2DirentName (
> {
>   CHAR8       Utf8NameBuf[EXT4_NAME_MAX + 1];
>   UINT16      *Str;
> +  UINTN       Index;

I *really* do not like UINTN in code that does not deal with buffer addresses and sizes. I'd change it to UINT8, but I'll leave it up to Pedro.

>   EFI_STATUS  Status;
> 
> -  CopyMem (Utf8NameBuf, Entry->name, Entry->name_len);
> +  for (Index = 0; Index < Entry->name_len; ++Index) {
> +    if (Entry->name[Index] == '\0') {
> +      return EFI_INVALID_PARAMETER;
> +    }
> +
> +    Utf8NameBuf[Index] = Entry->name[Index];
> +  }
> 
>   Utf8NameBuf[Entry->name_len] = '\0';
> 
> -- 
> 2.39.0
>