Re: [PATCH 5/5] fdisk: sgi: abort on HDIO_GETGEO failure

[Petr Uzel <petr.uzel@xxxxxxx>]

On Sun, May 06, 2012 at 02:10:25PM +0200, Davidlohr Bueso wrote:
> From: Davidlohr Bueso <dave@xxxxxxx>
> 
> When the HDIO_GETGEO ioctl fails on non IRIX/MIPS platforms (ie:
> inappropriate ioctl for device) the variables that describe the
> geometry are compromissed. One clear example is a division by 0 bug
> because the cylinder size is 0 is verify_sgi():

I agree with the change, however I think that more descriptive error
message should be printed; see below.

> 
> $> fdisk sgi.img
> Welcome to fdisk (util-linux 2.21.392-4b1c).
> 
> ...
> 
> Command (m for help): x
> 
> Expert command (m for help): g
> Building a new SGI disklabel.
> Partition 11 of type SGI volume and of size 7.9 MiB is set
> Floating point exception
> 
> Fix this by simply exiting the program instead of leaving it in a vulnerable state.
> 
> Signed-off-by: Davidlohr Bueso <dave@xxxxxxx>
> ---
>  fdisk/fdisksgilabel.c |   39 ++++++++++++++++++++-------------------
>  1 files changed, 20 insertions(+), 19 deletions(-)
> 
> diff --git a/fdisk/fdisksgilabel.c b/fdisk/fdisksgilabel.c
> index 822f55d..b61f102 100644
> --- a/fdisk/fdisksgilabel.c
> +++ b/fdisk/fdisksgilabel.c
> @@ -705,25 +705,26 @@ create_sgilabel(void)
>  	res = blkdev_get_sectors(fd, &llsectors);
>  
>  #ifdef HDIO_GETGEO
> -	if (!ioctl(fd, HDIO_GETGEO, &geometry)) {
> -		heads = geometry.heads;
> -		sectors = geometry.sectors;
> -		if (res == 0) {
> -			/* the get device size ioctl was successful */
> -			unsigned long long llcyls;
> -			llcyls = llsectors / (heads * sectors * sec_fac);
> -			cylinders = llcyls;
> -			if (cylinders != llcyls)	/* truncated? */
> -				cylinders = ~0;
> -		} else {
> -			/* otherwise print error and use truncated version */
> -			cylinders = geometry.cylinders;
> -			fprintf(stderr,
> -				_("Warning:  BLKGETSIZE ioctl failed on %s.  "
> -				  "Using geometry cylinder value of %d.\n"
> -				  "This value may be truncated for devices"
> -				  " > 33.8 GB.\n"), disk_device, cylinders);
> -		}
> +	if (ioctl(fd, HDIO_GETGEO, &geometry) < 0)
> +		err(EXIT_FAILURE, _("ioctl failed on %s"), disk_device);

s/"ioctl failed..."/"HDIO_GETGEO ioctl failed..."

[SNIP]

Petr

--
Petr Uzel
IRC: ptr_uzl @ freenode

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