[PATCH v2] pinctrl: fix deadlock in create_pinctrl() when handling -EPROBE_DEFER

[PATCH v2] pinctrl: fix deadlock in create_pinctrl() when handling -EPROBE_DEFER

[Hagar Hemdan]

In create_pinctrl(), pinctrl_maps_mutex is acquired before calling
add_setting(). If add_setting() returns -EPROBE_DEFER, create_pinctrl()
calls pinctrl_free(). However, pinctrl_free() attempts to acquire
pinctrl_maps_mutex, which is already held by create_pinctrl(), leading to
a potential deadlock.

This patch resolves the issue by releasing pinctrl_maps_mutex before
calling pinctrl_free(), preventing the deadlock.

This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.

Fixes: 42fed7ba44e4 ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Suggested-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
---
only compile tested
v2: Updated the commit msg.
---
 drivers/pinctrl/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index cffeb869130d..f424a57f0013 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -1106,8 +1106,8 @@ static struct pinctrl *create_pinctrl(struct device *dev,
 		 * an -EPROBE_DEFER later, as that is the worst case.
 		 */
 		if (ret == -EPROBE_DEFER) {
-			pinctrl_free(p, false);
 			mutex_unlock(&pinctrl_maps_mutex);
+			pinctrl_free(p, false);
 			return ERR_PTR(ret);
 		}
 	}
-- 
2.40.1

Re: [PATCH v2] pinctrl: fix deadlock in create_pinctrl() when handling -EPROBE_DEFER

[Linus Walleij]

On Tue, Jun 4, 2024 at 10:58 AM Hagar Hemdan <hagarhem@amazon.com> wrote:

> In create_pinctrl(), pinctrl_maps_mutex is acquired before calling
> add_setting(). If add_setting() returns -EPROBE_DEFER, create_pinctrl()
> calls pinctrl_free(). However, pinctrl_free() attempts to acquire
> pinctrl_maps_mutex, which is already held by create_pinctrl(), leading to
> a potential deadlock.
>
> This patch resolves the issue by releasing pinctrl_maps_mutex before
> calling pinctrl_free(), preventing the deadlock.
>
> This bug was discovered and resolved using Coverity Static Analysis
> Security Testing (SAST) by Synopsys, Inc.
>
> Fixes: 42fed7ba44e4 ("pinctrl: move subsystem mutex to pinctrl_dev struct")
> Suggested-by: Maximilian Heyne <mheyne@amazon.de>
> Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>

Looks like a real issue so patch applied for fixes.

Yours,
Linus Walleij