From: Stefan Haberland sth@linux.ibm.com
commit 952835edb4fdad49361d5330da918be8b765b787 upstream.
When new configuration data is obtained after a path event it is stored in the per path array. The old data needs to be freed. The first valid configuration data is also referenced in the device private structure to identify the device. When the old per path configuration data was freed the device still pointed to the already freed data leading to a use after free.
Fix by replacing also the device configuration data with the newly obtained one before the old data gets freed.
Fixes: 460181217a24 ("s390/dasd: Store path configuration data during path handling") Cc: stable@vger.kernel.org # 5.11+ Signed-off-by: Stefan Haberland sth@linux.ibm.com Reviewed-by: Jan Hoeppner hoeppner@linux.ibm.com Link: https://lore.kernel.org/r/20210804151800.4031761-2-sth@linux.ibm.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/block/dasd_eckd.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -1004,15 +1004,23 @@ static unsigned char dasd_eckd_path_acce static void dasd_eckd_store_conf_data(struct dasd_device *device, struct dasd_conf_data *conf_data, int chp) { + struct dasd_eckd_private *private = device->private; struct channel_path_desc_fmt0 *chp_desc; struct subchannel_id sch_id; + void *cdp;
- ccw_device_get_schid(device->cdev, &sch_id); /* * path handling and read_conf allocate data * free it before replacing the pointer + * also replace the old private->conf_data pointer + * with the new one if this points to the same data */ - kfree(device->path[chp].conf_data); + cdp = device->path[chp].conf_data; + if (private->conf_data == cdp) { + private->conf_data = (void *)conf_data; + dasd_eckd_identify_conf_parts(private); + } + ccw_device_get_schid(device->cdev, &sch_id); device->path[chp].conf_data = conf_data; device->path[chp].cssid = sch_id.cssid; device->path[chp].ssid = sch_id.ssid; @@ -1020,6 +1028,7 @@ static void dasd_eckd_store_conf_data(st if (chp_desc) device->path[chp].chpid = chp_desc->chpid; kfree(chp_desc); + kfree(cdp); }
static void dasd_eckd_clear_conf_data(struct dasd_device *device)