On Mon, Nov 10, 2025 at 2:38 AM, Michael Chang <[email protected]> wrote:
> The grub_strtol() call in blsuki_is_default_entry() can set grub_errno
> to GRUB_ERR_BAD_NUMBER if the input string cannot be converted into any
> valid digits.
> 
> This errno value is currently left uncleared, which can lead to
> unexpected behavior in subsequent logic that tests the result of a
> function by checking grub_errno.
> 
> Clear grub_errno and return false when GRUB_ERR_BAD_NUMBER is set, as
> this specific error should be ignored in this context.

grub_strtol() can also set grub_errno to GRUB_ERR_OUT_OF_RANGE. Would it make
sense to check for that as well? We do return false if def_idx is negative
or larger than GRUB_INT_MAX, but I don't know if we would want to sustain
GRUB_ERR_OUT_OF_RANGE in grub_errno past this function should the "def_entry"
passed into this function contain a bad value that causes grub_strtol() to give
an error.

Alec Brown

> 
> Signed-off-by: Michael Chang <[email protected]>
> ---
>  grub-core/commands/blsuki.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/grub-core/commands/blsuki.c b/grub-core/commands/blsuki.c
> index 21d767f05..df25b6fbc 100644
> --- a/grub-core/commands/blsuki.c
> +++ b/grub-core/commands/blsuki.c
> @@ -1510,6 +1510,12 @@ blsuki_is_default_entry (const char *def_entry, 
> grub_blsuki_entry_t *entry,
> int
>      return true;
> 
>    def_idx = grub_strtol (def_entry, &def_entry_end, 0);
> +  if (grub_errno == GRUB_ERR_BAD_NUMBER)
> +    {
> +      grub_errno = GRUB_ERR_NONE;
> +      return false;
> +    }
> +
>    if (*def_entry_end != '\0' || def_idx < 0 || def_idx > GRUB_INT_MAX)
>      return false;
> 
> --
> 2.51.1
> 
> 
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