linux-kernel - [PATCH] watchdog: Fix double-free in watchdog_cdev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 23 Aug 2020 15:13:38 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Alexander Sverdlin <alexander.sverdlin@...ia.com>,
        Krzysztof Sobota <krzysztof.sobota@...ia.com>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] watchdog: Fix double-free in watchdog_cdev_register

When misc_register() fails, wd_data will be released by the
release callback function watchdog_core_data_release(), so
we don't need to free it again. But when watchdog_kworker is
NULL, we should free wd_data to prevent memleak.

Fixes: cb36e29bb0e4b ("watchdog: initialize device before misc_register")
Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
---
 drivers/watchdog/watchdog_dev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6798addabd5a..8ee78e26feb1 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -994,8 +994,10 @@ static int watchdog_cdev_register(struct watchdog_device *wdd)
 	wd_data->wdd = wdd;
 	wdd->wd_data = wd_data;
 
-	if (IS_ERR_OR_NULL(watchdog_kworker))
+	if (IS_ERR_OR_NULL(watchdog_kworker)) {
+		kfree(wd_data);
 		return -ENODEV;
+	}
 
 	device_initialize(&wd_data->dev);
 	wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id);
@@ -1021,7 +1023,6 @@ static int watchdog_cdev_register(struct watchdog_device *wdd)
 				pr_err("%s: a legacy watchdog module is probably present.\n",
 					wdd->info->identity);
 			old_wd_data = NULL;
-			kfree(wd_data);
 			return err;
 		}
 	}
-- 
2.17.1