[1/1] fs: fat_write: fix short name creation.

Truncate file names if the buffer size is exceeded to avoid a buffer
overflow.

Use Sphinx style function description.

Add a TODO comment.

Reported-by: CID 303779
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 fs/fat/fat_write.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

--
2.26.2

Hi Heinrich,

On Tue, 26 May 2020 at 13:12, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> Truncate file names if the buffer size is exceeded to avoid a buffer
> overflow.
>
> Use Sphinx style function description.
>
> Add a TODO comment.
>
> Reported-by: CID 303779
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
>  fs/fat/fat_write.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)

Reviewed-by: Simon Glass <sjg at chromium.org>

See below

>
> diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
> index 59cc0bae94..b16a39d3ff 100644
> --- a/fs/fat/fat_write.c
> +++ b/fs/fat/fat_write.c
> @@ -50,8 +50,11 @@ static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
>         return ret;
>  }
>
> -/*
> - * Set short name in directory entry
> +/**
> + * set_name() - set short name in directory entry
> + *
> + * @dirent:    directory entry
> + * @filename:  long file name
>   */
>  static void set_name(dir_entry *dirent, const char *filename)
>  {
> @@ -66,7 +69,8 @@ static void set_name(dir_entry *dirent, const char *filename)
>         if (len == 0)
>                 return;
>
> -       strcpy(s_name, filename);
> +       strncpy(s_name, filename, VFAT_MAXLEN_BYTES - 1);
> +       s_name[VFAT_MAXLEN_BYTES - 1] = '\0';

Could use strlcpy() here

>         uppercase(s_name, len);
>
>         period = strchr(s_name, '.');
> @@ -87,6 +91,11 @@ static void set_name(dir_entry *dirent, const char *filename)
>                 memcpy(dirent->name, s_name, period_location);
>         } else {
>                 memcpy(dirent->name, s_name, 6);
> +               /*
> +                * TODO: Translating two long names with the same first six
> +                *       characters to the same short name is utterly wrong.
> +                *       Short names must be unique.
> +                */
>                 dirent->name[6] = '~';
>                 dirent->name[7] = '1';
>         }
> --
> 2.26.2
>

Regards,
Simon