cdrom: information leak in cdrom_ioctl_media_changed()

commit 9de4ee40547fd315d4a0ed1dd15a2fa3559ad707 upstream.

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>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index a03e849..3792f5c 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2342,7 +2342,7 @@ 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 (!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);
                return -EINVAL;
 
        info = kmalloc(sizeof(*info), GFP_KERNEL);