[PATCH] watchdog: intel_oc_wdt: Do not try to write into const memory

[PATCH] watchdog: intel_oc_wdt: Do not try to write into const memory

[Guenter Roeck]

The code tries to update the intel_oc_wdt_info data structure if the
watchdog is locked. That data structure is marked as const and can not
be written into. Copy it into struct intel_oc_wdt and modify it there
to fix the problem.

Reported-by: Petar Kulić <cooleech@gmail.com>
Cc: Diogo Ivo <diogo.ivo@siemens.com>
Fixes: 535d1784d8a9 ("watchdog: Add driver for Intel OC WDT")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
I don't know if this fixes the reported problem, so no Closes:
tag, but the code is wrong either way and needs to be fixed.

 drivers/watchdog/intel_oc_wdt.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/intel_oc_wdt.c b/drivers/watchdog/intel_oc_wdt.c
index 7c0551106981..a39892c10770 100644
--- a/drivers/watchdog/intel_oc_wdt.c
+++ b/drivers/watchdog/intel_oc_wdt.c
@@ -41,6 +41,7 @@
 struct intel_oc_wdt {
 	struct watchdog_device wdd;
 	struct resource *ctrl_res;
+	struct watchdog_info info;
 	bool locked;
 };
 
@@ -115,7 +116,6 @@ static const struct watchdog_ops intel_oc_wdt_ops = {
 
 static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
 {
-	struct watchdog_info *info;
 	unsigned long val;
 
 	val = inl(INTEL_OC_WDT_CTRL_REG(oc_wdt));
@@ -134,7 +134,6 @@ static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
 		set_bit(WDOG_HW_RUNNING, &oc_wdt->wdd.status);
 
 		if (oc_wdt->locked) {
-			info = (struct watchdog_info *)&intel_oc_wdt_info;
 			/*
 			 * Set nowayout unconditionally as we cannot stop
 			 * the watchdog.
@@ -145,7 +144,7 @@ static int intel_oc_wdt_setup(struct intel_oc_wdt *oc_wdt)
 			 * and inform the core we can't change it.
 			 */
 			oc_wdt->wdd.timeout = (val & INTEL_OC_WDT_TOV) + 1;
-			info->options &= ~WDIOF_SETTIMEOUT;
+			oc_wdt->info.options &= ~WDIOF_SETTIMEOUT;
 
 			dev_info(oc_wdt->wdd.parent,
 				 "Register access locked, heartbeat fixed at: %u s\n",
@@ -193,7 +192,8 @@ static int intel_oc_wdt_probe(struct platform_device *pdev)
 	wdd->min_timeout = INTEL_OC_WDT_MIN_TOV;
 	wdd->max_timeout = INTEL_OC_WDT_MAX_TOV;
 	wdd->timeout = INTEL_OC_WDT_DEF_TOV;
-	wdd->info = &intel_oc_wdt_info;
+	oc_wdt->info = intel_oc_wdt_info;
+	wdd->info = &oc_wdt->info;
 	wdd->ops = &intel_oc_wdt_ops;
 	wdd->parent = dev;
 
-- 
2.45.2

Re: [PATCH] watchdog: intel_oc_wdt: Do not try to write into const memory

[Diogo Ivo]

To make it explicit with my comments on [1]:

Reviewed-by: Diogo Ivo <diogo.ivo@siemens.com>
Tested-by: Diogo Ivo <diogo.ivo@siemens.com>

[1]: https://lore.kernel.org/linux-watchdog/20250818031838.3359-1-diogo.ivo@tecnico.ulisboa.pt/T/#t