Re: [PATCH 4.7 146/186] floppy: fix open(O_ACCMODE) for ioctl-only open

[Mark Hounschell]

On 08/18/2016 09:59 AM, Greg Kroah-Hartman wrote:
> 4.7-stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Jiri Kosina <jkosina@xxxxxxx>
>
> commit ff06db1efb2ad6db06eb5b99b88a0c15a9cc9b0e upstream.
>
> Commit 09954bad4 ("floppy: refactor open() flags handling"), as a
> side-effect, causes open(/dev/fdX, O_ACCMODE) to fail. It turns out that
> this is being used setfdprm userspace for ioctl-only open().
>
> Reintroduce back the original behavior wrt !(FMODE_READ|FMODE_WRITE)
> modes, while still keeping the original O_NDELAY bug fixed.
>
> Reported-by: Wim Osterholt <wim@xxxxxxxxxxxxxx>
> Tested-by: Wim Osterholt <wim@xxxxxxxxxxxxxx>
> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> Signed-off-by: Jens Axboe <axboe@xxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
>  drivers/block/floppy.c |   21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
>
> --- a/drivers/block/floppy.c
> +++ b/drivers/block/floppy.c
> @@ -3663,11 +3663,6 @@ static int floppy_open(struct block_devi
>
>  	opened_bdev[drive] = bdev;
>
> -	if (!(mode & (FMODE_READ|FMODE_WRITE))) {
> -		res = -EINVAL;
> -		goto out;
> -	}
> -
>  	res = -ENXIO;
>
>  	if (!floppy_track_buffer) {
> @@ -3711,13 +3706,15 @@ static int floppy_open(struct block_devi
>  	if (UFDCS->rawcmd == 1)
>  		UFDCS->rawcmd = 2;
>
> -	UDRS->last_checked = 0;
> -	clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);
> -	check_disk_change(bdev);
> -	if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags))
> -		goto out;
> -	if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags))
> -		goto out;
> +	if (mode & (FMODE_READ|FMODE_WRITE)) {
> +		UDRS->last_checked = 0;
> +		clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags);
> +		check_disk_change(bdev);
> +		if (test_bit(FD_DISK_CHANGED_BIT, &UDRS->flags))
> +			goto out;
> +		if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &UDRS->flags))
> +			goto out;
> +	}
>
>  	res = -EROFS;

I have a problem with this patch. It only fixes one of the regressions 
caused by the original change to the floppy driver. It does not address 
the user land breakage of removing the NODELAY flag checks.

Thanks
Mark