linux-kernel - [PATCH][next] pinctrl: th1520: Fix potential null pointer dereference on func

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Message-Id: <20241016155655.334518-1-colin.i.king@gmail.com>
Date: Wed, 16 Oct 2024 16:56:55 +0100
From: Colin Ian King <colin.i.king@...il.com>
To: Drew Fustini <drew@...7.com>,
	Guo Ren <guoren@...nel.org>,
	Fu Wei <wefu@...hat.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Emil Renner Berthing <emil.renner.berthing@...onical.com>,
	linux-riscv@...ts.infradead.org,
	linux-gpio@...r.kernel.org
Cc: kernel-janitors@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH][next] pinctrl: th1520: Fix potential null pointer dereference on func

The initialization of muxtype deferences pointer func before func
is sanity checked with a null pointer check, hence we have a null
pointer deference issue. Fix this by only deferencing func with
the assignment to muxtype after func has been null pointer checked.

Fixes: 1fc30cd92770 ("pinctrl: th1520: Factor out casts")
Signed-off-by: Colin Ian King <colin.i.king@...il.com>
---
 drivers/pinctrl/pinctrl-th1520.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/pinctrl-th1520.c b/drivers/pinctrl/pinctrl-th1520.c
index 7474d8da32f9..e641bad6728c 100644
--- a/drivers/pinctrl/pinctrl-th1520.c
+++ b/drivers/pinctrl/pinctrl-th1520.c
@@ -803,11 +803,12 @@ static int th1520_pinmux_set_mux(struct pinctrl_dev *pctldev,
 {
 	struct th1520_pinctrl *thp = pinctrl_dev_get_drvdata(pctldev);
 	const struct function_desc *func = pinmux_generic_get_function(pctldev, fsel);
-	enum th1520_muxtype muxtype = (uintptr_t)func->data;
+	enum th1520_muxtype muxtype;
 
 	if (!func)
 		return -EINVAL;
 
+	muxtype = (uintptr_t)func->data;
 	return th1520_pinmux_set(thp, thp->desc.pins[gsel].number,
 				 th1520_pad_muxdata(thp->desc.pins[gsel].drv_data),
 				 muxtype);
-- 
2.39.5