cdrom: information leak in cdrom_ioctl_media_changed()

This cast is wrong.  "cdi->capacity" is an int and "arg" is an unsigned
long.  The way the check is written now, if one of the high 32 bits is
set then we could read outside the info->slots[] array.

This bug is pretty old and it predates git.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 8327478effd0b1c7da0b892a3b857cd6423e5a88..bfc566d3f31a40cf5b89d9284b2538644af68dee 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2371,7 +2371,7 @@ static int cdrom_ioctl_media_changed(struct cdrom_device_info *cdi,
        if (!CDROM_CAN(CDC_SELECT_DISC) || arg == CDSL_CURRENT)
                return media_changed(cdi, 1);
 
-       if ((unsigned int)arg >= cdi->capacity)
+       if (arg >= cdi->capacity)
                return -EINVAL;
 
        info = kmalloc(sizeof(*info), GFP_KERNEL);