From: madhuparnabhowmik10@gmail.com
To: wim@linux-watchdog.org, linux@roeck-us.net
Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org,
andrianov@ispras.ru, ldv-project@linuxtesting.org,
Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Subject: [PATCH] drivers: watchdog: pc87413_wdt: Fix Race condition bug
Date: Thu, 13 Aug 2020 18:24:51 +0530 [thread overview]
Message-ID: <20200813125451.19118-1-madhuparnabhowmik10@gmail.com> (raw)
From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
After misc_register the open() callback can be called.
However the base address (swc_base_addr) is set after misc_register()
in init.
As a result, if open callback is called before pc87413_get_swc_base_addr()
then in the following call chain: pc87413_open() -> pc87413_refresh() ->
pc87413_swc_bank3() : The value of swc_base_addr will be -1.
Therefore, do misc_register() after pc87413_get_swc_base_addr().
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
---
drivers/watchdog/pc87413_wdt.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/watchdog/pc87413_wdt.c b/drivers/watchdog/pc87413_wdt.c
index 73fbfc99083b..ad8b8af2bdc0 100644
--- a/drivers/watchdog/pc87413_wdt.c
+++ b/drivers/watchdog/pc87413_wdt.c
@@ -512,6 +512,10 @@ static int __init pc87413_init(void)
if (ret != 0)
pr_err("cannot register reboot notifier (err=%d)\n", ret);
+ pc87413_select_wdt_out();
+ pc87413_enable_swc();
+ pc87413_get_swc_base_addr();
+
ret = misc_register(&pc87413_miscdev);
if (ret != 0) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
@@ -520,10 +524,6 @@ static int __init pc87413_init(void)
}
pr_info("initialized. timeout=%d min\n", timeout);
- pc87413_select_wdt_out();
- pc87413_enable_swc();
- pc87413_get_swc_base_addr();
-
if (!request_region(swc_base_addr, 0x20, MODNAME)) {
pr_err("cannot request SWC region at 0x%x\n", swc_base_addr);
ret = -EBUSY;
--
2.17.1
next reply other threads:[~2020-08-13 12:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 12:54 madhuparnabhowmik10 [this message]
2020-08-14 15:07 ` [PATCH] drivers: watchdog: pc87413_wdt: Fix Race condition bug Guenter Roeck
2020-08-16 7:24 ` Madhuparna Bhowmik
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