linux-kernel - [PATCH][next] gpio: sim: Fix dereference of free'd pointer config

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Date:   Tue, 27 Apr 2021 11:24:27 +0100
From:   Colin King <colin.king@...onical.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-gpio@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] gpio: sim: Fix dereference of free'd pointer config

From: Colin Ian King <colin.king@...onical.com>

The error return of config->id dereferences the kfree'd object config.
Fix this by using a temporary variable for the id to avoid this issue.

Addresses-Coverity: ("Read from pointer aftyer free")
Fixes: a49d14276ac4 ("gpio: sim: allocate IDA numbers earlier")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpio/gpio-sim.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 2e2e6399e453..7bba5783a043 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -751,8 +751,10 @@ gpio_sim_config_make_item(struct config_group *group, const char *name)
 
 	config->id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
 	if (config->id < 0) {
+		int id = config->id;
+
 		kfree(config);
-		return ERR_PTR(config->id);
+		return ERR_PTR(id);
 	}
 
 	config_item_init_type_name(&config->item, name,
-- 
2.30.2