[PATCH] floppy: return the drive state flags from the 32-bit FDGETDRVSTAT

["Denis Efremov (Oracle)" <efremov@linux.com>]

compat_getdrvstat() copies every field of the drive state to a 32-bit
caller except ->flags, which stays zero. 32-bit FDGETDRVSTAT and
FDPOLLDRVSTAT therefore never report FD_DISK_WRITABLE, FD_DISK_CHANGED
or FD_VERIFY: i386 fdutils (floppycontrol -P, fdmount), and other
32-bit users see every disk as write-protected and never see a disk
change. The compat code in block/compat_ioctl.c copied the field;
it was lost when that code moved into floppy.c

Also declare the field as compat_ulong_t: the 32-bit struct
floppy_drive_struct starts with an unsigned long, and a signed char at
offset 0 only lines up with its low byte on little-endian machines. The
size and offsets of the compat structure, and so FDGETDRVSTAT32, do not
change.

Cc: stable@vger.kernel.org
Fixes: 229b53c9bf4e ("take floppy compat ioctls to sodding floppy.c")
Signed-off-by: Denis Efremov (Oracle) <efremov@linux.com>
---
 drivers/block/floppy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index f04397b8e381..569e8823dd3f 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3601,7 +3601,7 @@ struct compat_floppy_drive_params {
 };
 
 struct compat_floppy_drive_struct {
-	signed char	flags;
+	compat_ulong_t	flags;
 	compat_ulong_t	spinup_date;
 	compat_ulong_t	select_date;
 	compat_ulong_t	first_read_date;
@@ -3785,6 +3785,7 @@ static int compat_getdrvstat(int drive, bool poll,
 			goto Eintr;
 		process_fd_request();
 	}
+	v.flags = drive_state[drive].flags;
 	v.spinup_date = drive_state[drive].spinup_date;
 	v.select_date = drive_state[drive].select_date;
 	v.first_read_date = drive_state[drive].first_read_date;

base-commit: 62f4c998b297cf233997a2b4cd6fc2d2df0319c9
-- 
2.55.0