pinctrl: fix deadlock in create_pinctrl() when handling -EPROBE_DEFER

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>
Link: https://lore.kernel.org/r/20240604085838.3344-1-hagarhem@amazon.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index cffeb86..f424a57 100644 (file)
--- 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);
                }
        }