s390/dasd: fix memleak in path handling error case

This change “s390/dasd: fix memleak in path handling error case” (commit 00b39f6) in Linux kernel is authored by Stefan Haberland <sth [at] linux.ibm.com> on Thu Dec 19 09:43:51 2019 +0100.

Description of "s390/dasd: fix memleak in path handling error case"

The change “s390/dasd: fix memleak in path handling error case” introduces changes as follows.

s390/dasd: fix memleak in path handling error case

If for whatever reason the dasd_eckd_check_characteristics() function
exits after at least some paths have their configuration data
allocated those data is never freed again. In the error case the
device->private pointer is set to NULL and dasd_eckd_uncheck_device()
will exit without freeing the path data because of this NULL pointer.

Fix by calling dasd_eckd_clear_conf_data() for error cases.

Also use dasd_eckd_clear_conf_data() in dasd_eckd_uncheck_device()
to avoid code duplication.

Reported-by: Qian Cai <cai@lca.pw>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Linux kernel releases containing commit 00b39f6

The Linux kernel releases containing this commit are as follows.

Linux kernel code changes from "s390/dasd: fix memleak in path handling error case"

There are 19 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/s390/block/dasd_eckd.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)
 
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index f5622f4a2ecf..a28b9ff82378 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -2074,7 +2074,7 @@ dasd_eckd_check_characteristics(struct dasd_device *device)
 	dasd_free_block(device->block);
 	device->block = NULL;
 out_err1:
-	kfree(private->conf_data);
+	dasd_eckd_clear_conf_data(device);
 	kfree(device->private);
 	device->private = NULL;
 	return rc;
@@ -2083,7 +2083,6 @@ dasd_eckd_check_characteristics(struct dasd_device *device)
 static void dasd_eckd_uncheck_device(struct dasd_device *device)
 {
 	struct dasd_eckd_private *private = device->private;
-	int i;
 
 	if (!private)
 		return;
@@ -2093,21 +2092,7 @@ static void dasd_eckd_uncheck_device(struct dasd_device *device)
 	private->sneq = NULL;
 	private->vdsneq = NULL;
 	private->gneq = NULL;
-	private->conf_len = 0;
-	for (i = 0; i < 8; i++) {
-		kfree(device->path[i].conf_data);
-		if ((__u8 *)device->path[i].conf_data ==
-		    private->conf_data) {
-			private->conf_data = NULL;
-			private->conf_len = 0;
-		}
-		device->path[i].conf_data = NULL;
-		device->path[i].cssid = 0;
-		device->path[i].ssid = 0;
-		device->path[i].chpid = 0;
-	}
-	kfree(private->conf_data);
-	private->conf_data = NULL;
+	dasd_eckd_clear_conf_data(device);
 }
 
 static struct dasd_ccw_req *

The commit for this change in Linux stable tree is 00b39f6 (patch).

Last modified: 2020/02/08