block/scsi-ioctl: Fix kernel-infoleak in scsi_put_cdrom_generic_arg()

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@vger.kernel.org
Fixes: f3ee6e63a9df ("compat_ioctl: move CDROM_SEND_PACKET handling into scsi")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: syzbot+85433a479a646a064ab3@syzkaller.appspotmail.com
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index ef722f04f88a93b38d2c3df4f503dea5da05ffbd..72108404718fe717a249584fdbd32b676cc310c8 100644 (file)
--- 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];