[PATCH 5.8 012/124] block/scsi-ioctl: Fix kernel-infoleak in scsi_put_cdrom_generic_arg()

[Greg Kroah-Hartman]

From: Peilin Ye <yepeilin.cs@xxxxxxxxx>

commit 6d53a9fe5a1983490bc14b3a64d49fabb4ccc651 upstream.

scsi_put_cdrom_generic_arg() is copying uninitialized stack memory to
userspace, since the compiler may leave a 3-byte hole in the middle of
`cgc32`. Fix it by adding a padding field to `struct
compat_cdrom_generic_command`.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: f3ee6e63a9df ("compat_ioctl: move CDROM_SEND_PACKET handling into scsi")
Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
Reported-by: syzbot+85433a479a646a064ab3@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 block/scsi_ioctl.c |    1 +
 1 file changed, 1 insertion(+)

--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -651,6 +651,7 @@ struct compat_cdrom_generic_command {
 	compat_int_t	stat;
 	compat_caddr_t	sense;
 	unsigned char	data_direction;
+	unsigned char	pad[3];
 	compat_int_t	quiet;
 	compat_int_t	timeout;
 	compat_caddr_t	reserved[1];