Re: [PATCH] Fix prefix autodetection when booting from EFI CD-ROM

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 31.01.2013 13:24, Andrey Borzenkov wrote:

> Fix autodetection of $prefix when booted from EFI CD-ROM.
> 
> Based on patch from Matthew Garrett, modified to not overwrite
> memory returned by device path protocol handler and rebased to
> current trunk.

Due to legal issues we need Matthew Garrett, or someone from Red Hat, to
send the patch. I wonder why this didn't happen before.

> 
> Additionally fixes potential memory leak - dup_dp was not deallocated
> if device path was not found.
> 
> Signed-off-by: Andrey Borzenkov <address@hidden>
> 
> ---
>  grub-core/disk/efi/efidisk.c |  121 
> +++++++++++++++++++++++-------------------
>  1 file changed, 66 insertions(+), 55 deletions(-)
> 
> diff --git a/grub-core/disk/efi/efidisk.c b/grub-core/disk/efi/efidisk.c
> index 98cd226..15c8109 100644
> --- a/grub-core/disk/efi/efidisk.c
> +++ b/grub-core/disk/efi/efidisk.c
> @@ -775,67 +775,78 @@ grub_efidisk_get_device_name (grub_efi_handle_t *handle)
>    if (! ldp)
>      return 0;
>  
> -  if (GRUB_EFI_DEVICE_PATH_TYPE (ldp) == GRUB_EFI_MEDIA_DEVICE_PATH_TYPE
> -      && (GRUB_EFI_DEVICE_PATH_SUBTYPE (ldp)
> -       == GRUB_EFI_HARD_DRIVE_DEVICE_PATH_SUBTYPE))
> +  if (GRUB_EFI_DEVICE_PATH_TYPE (ldp) == GRUB_EFI_MEDIA_DEVICE_PATH_TYPE)
>      {
> -      struct grub_efidisk_get_device_name_ctx ctx;
> -      char *dev_name;
> -      grub_efi_device_path_t *dup_dp, *dup_ldp;
> -      grub_disk_t parent = 0;
> -
> -      /* It is necessary to duplicate the device path so that GRUB
> -      can overwrite it.  */
> -      dup_dp = duplicate_device_path (dp);
> -      if (! dup_dp)
> -     return 0;
> -
> -      dup_ldp = find_last_device_path (dup_dp);
> -      dup_ldp->type = GRUB_EFI_END_DEVICE_PATH_TYPE;
> -      dup_ldp->subtype = GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE;
> -      dup_ldp->length[0] = sizeof (*dup_ldp);
> -      dup_ldp->length[1] = 0;
> +      int is_cdrom = 0;
>  
> -      if (!get_diskname_from_path (dup_dp, device_name))
> -     return 0;
> -      parent = grub_disk_open (device_name);
> -      grub_free (dup_dp);
> -
> -      if (! parent)
> -     return 0;
> -
> -      /* Find a partition which matches the hard drive device path.  */
> -      ctx.partition_name = NULL;
> -      grub_memcpy (&ctx.hd, ldp, sizeof (ctx.hd));
> -      if (ctx.hd.partition_start == 0
> -       && ctx.hd.partition_size == grub_disk_get_size (parent))
> -     {
> -       dev_name = grub_strdup (parent->name);
> -     }
> -      else
> +      switch (GRUB_EFI_DEVICE_PATH_SUBTYPE (ldp))
>       {
> -       grub_partition_iterate (parent, grub_efidisk_get_device_name_iter,
> -                               &ctx);
> -
> -       if (! ctx.partition_name)
> +       case GRUB_EFI_CDROM_DEVICE_PATH_SUBTYPE:
> +         is_cdrom = 1;
> +         /* Intentionally fall through */
> +       case GRUB_EFI_HARD_DRIVE_DEVICE_PATH_SUBTYPE:
>           {
> +           struct grub_efidisk_get_device_name_ctx ctx;
> +           char *dev_name;
> +           grub_efi_device_path_t *dup_dp, *dup_ldp;
> +           grub_disk_t parent = 0;
> +
> +           /* It is necessary to duplicate the device path so that GRUB
> +              can overwrite it.  */
> +           dup_dp = duplicate_device_path (dp);
> +           if (! dup_dp)
> +             return 0;
> +
> +           dup_ldp = find_last_device_path (dup_dp);
> +           dup_ldp->type = GRUB_EFI_END_DEVICE_PATH_TYPE;
> +           dup_ldp->subtype = GRUB_EFI_END_ENTIRE_DEVICE_PATH_SUBTYPE;
> +           dup_ldp->length[0] = sizeof (*dup_ldp);
> +           dup_ldp->length[1] = 0;
> +
> +           if (!get_diskname_from_path (dup_dp, device_name))
> +             {
> +               grub_free (dup_dp);
> +               return 0;
> +             }
> +           grub_free (dup_dp);
> +           if (is_cdrom)
> +             return grub_strdup (device_name);
> +
> +           parent = grub_disk_open (device_name);
> +           if (! parent)
> +             return 0;
> +
> +           /* Find a partition which matches the hard drive device path.  */
> +           ctx.partition_name = NULL;
> +           grub_memcpy (&ctx.hd, ldp, sizeof (ctx.hd));
> +           if (ctx.hd.partition_start == 0
> +               && ctx.hd.partition_size == grub_disk_get_size (parent))
> +             {
> +               dev_name = grub_strdup (parent->name);
> +             }
> +           else
> +             {
> +               grub_partition_iterate (parent, 
> grub_efidisk_get_device_name_iter,
> +                                       &ctx);
> +
> +               if (! ctx.partition_name)
> +                 {
> +                   grub_disk_close (parent);
> +                   return 0;
> +                 }
> +
> +               dev_name = grub_xasprintf ("%s,%s", parent->name,
> +                                          ctx.partition_name);
> +               grub_free (ctx.partition_name);
> +             }
>             grub_disk_close (parent);
> -           return 0;
> -         }
>  
> -       dev_name = grub_xasprintf ("%s,%s", parent->name,
> -                                  ctx.partition_name);
> -       grub_free (ctx.partition_name);
> +           return dev_name;
> +         }
>       }
> -      grub_disk_close (parent);
> -
> -      return dev_name;
> -    }
> -  else
> -    {
> -      /* This should be an entire disk.  */
> -      if (!get_diskname_from_path (dp, device_name))
> -     return 0;
> -      return grub_strdup (device_name);
>      }
> +  /* This may be guessed device - floppy, cdrom or entire disk.  */
> +  if (!get_diskname_from_path (dp, device_name))
> +    return 0;
> +  return grub_strdup (device_name);
>  }



-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko

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