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

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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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 <arvidjaar@gmail.com>
> 
> ---
>  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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