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Fri, 13 Feb 2026 09:30:10 -0800 (PST) Received: from dianders.sjc.corp.google.com ([2a00:79e0:2e7c:8:d300:8e6:51e6:35df]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1272a6f3279sm6371734c88.13.2026.02.13.09.30.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Feb 2026 09:30:09 -0800 (PST) From: Douglas Anderson To: Linus Walleij , Christian Brauner , Bartosz Golaszewski , Kent Gibson Cc: Douglas Anderson , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] gpio: Avoid NULL dereference in linehandle_create() Date: Fri, 13 Feb 2026 09:29:31 -0800 Message-ID: <20260213092930.1.I77c3eb563271c21870379eefd16ebbc4e09635bb@changeid> X-Mailer: git-send-email 2.53.0.273.g2a3d683680-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In linehandle_create(), there is a statement like this: retain_and_null_ptr(lh); Soon after, there is a debug printout that dereferences "lh", which will crash things. Avoid the crash by reading value needed by the printout before making "lh" NULL. Fixes: da7e394bf58f ("gpio: convert linehandle_create() to FD_PREPARE()") Signed-off-by: Douglas Anderson --- drivers/gpio/gpiolib-cdev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index 2adc3c070908..13ab6a5ebb76 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -304,6 +304,7 @@ static int linehandle_create(struct gpio_device *gdev, = void __user *ip) { struct gpiohandle_request handlereq; struct linehandle_state *lh __free(linehandle_free) =3D NULL; + u32 num_descs; int i, ret; u32 lflags; =20 @@ -379,6 +380,7 @@ static int linehandle_create(struct gpio_device *gdev, = void __user *ip) lh, O_RDONLY | O_CLOEXEC)); if (fdf.err) return fdf.err; + num_descs =3D lh->num_descs; retain_and_null_ptr(lh); =20 handlereq.fd =3D fd_prepare_fd(fdf); @@ -388,7 +390,7 @@ static int linehandle_create(struct gpio_device *gdev, = void __user *ip) fd_publish(fdf); =20 dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n", - lh->num_descs); + num_descs); =20 return 0; } --=20 2.53.0.273.g2a3d683680-goog