Re: [PATCH] efi: check *path non-null before grub_strrchr

[Andrei Borzenkov]

On Wed, Nov 5, 2014 at 3:53 PM, Leif Lindholm <address@hidden> wrote:
> The EFI version of grub_machine_get_bootlocation crops the boot image
> name back to the last / in order to get a directory path. However, it
> does not check that *name is actually set before calling grub_strrchr
> to do this, and neither does grub_strrchr before dereferencing a NULL
> pointer.
>

I wonder - do you actually have firmware that returns empty path?

> Parent function, grub_set_prefix_and_root, does check the pointer
> before using.
>
> Signed-off-by: Leif Lindholm <address@hidden>
> ---
>  grub-core/kern/efi/init.c |   11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
> index 942ab02..e9c85de 100644
> --- a/grub-core/kern/efi/init.c
> +++ b/grub-core/kern/efi/init.c
> @@ -63,10 +63,13 @@ grub_machine_get_bootlocation (char **device, char
> **path)
>    if (!*device && grub_efi_net_config)
>      grub_efi_net_config (image->device_handle, device, path);
>
> -  /* Get the directory.  */
> -  p = grub_strrchr (*path, '/');
> -  if (p)
> -    *p = '\0';
> +  if (*path)
> +    {
> +      /* Get the directory.  */
> +      p = grub_strrchr (*path, '/');
> +      if (p)
> +        *p = '\0';
> +    }
>  }
>
>  void
> --
> 1.7.10.4
>
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