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Sun, 06 Sep 2026 04:41:59 -0700 (PDT) Message-ID: <6a9d5187.d63de05c.175391.a17c@mx.google.com> X-Mailer: git-send-email 2.46.2.windows.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Manush Prajwal" To: ukleinek@kernel.org Cc: linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org Date: 6 Sep 2026 17:11:58 +0530 Subject: [PATCH] pwm: lp3943: fix NULL pointer dereference for an unconfigured channel Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable lp3943_pwm_probe() unconditionally registers a pwmchip with=0D=0A= LP3943_NUM_PWMS(2) hwpwm channels, but lp3943_pwm_parse_dt() only= =0D=0Apopulates pdata->pwms[i] for the channels whose ti,pwm0/ti,= pwm1=0D=0Aproperty is actually present in the devicetree (the bin= ding=0D=0Aexplicitly allows each PWM generator to drive zero or m= ore outputs,=0D=0Aand lp3943_pwm_parse_dt() only fails outright w= ith -ENODATA if=0D=0A*neither* property is present). A devicetree= that configures only one=0D=0Aof the two channels leaves pdata->= pwms[] NULL for the other.=0D=0A=0D=0Alp3943_pwm_request_map() de= references pdata->pwms[hwpwm] with no NULL=0D=0Acheck:=0D=0A=0D=0A= pwm_map->output =3D pdata->pwms[hwpwm]->output;=0D=0A pwm_map->n= um_outputs =3D pdata->pwms[hwpwm]->num_outputs;=0D=0A=0D=0Aso req= uesting the unconfigured channel (e.g. exporting it from=0D=0Asys= fs) crashes with a NULL pointer dereference instead of failing=0D=0A= cleanly.=0D=0A=0D=0AReturn -ENODEV from lp3943_pwm_request_map() = when the channel was=0D=0Anever configured, before the pointer is= dereferenced. The caller,=0D=0Alp3943_pwm_request(), already pro= pagates an ERR_PTR return correctly=0D=0A(it does so today for th= e existing -EBUSY case).=0D=0A=0D=0AReported-by: Sashiko AI revie= w =0D=0ACloses: https://sashiko.dev/#/pat= chset/6a9d4c6b.79b5ea6e.147aa1.5883@mx.google.com?part=3D1=0D=0AS= igned-off-by: Manush Prajwal =0D=0A--= -=0D=0A drivers/pwm/pwm-lp3943.c | 3 +++=0D=0A 1 file changed, 3 = insertions(+)=0D=0A=0D=0Adiff --git a/drivers/pwm/pwm-lp3943.c b/= drivers/pwm/pwm-lp3943.c=0D=0Aindex e8bb8dbb9..956d22053 100644=0D=0A= --- a/drivers/pwm/pwm-lp3943.c=0D=0A+++ b/drivers/pwm/pwm-lp3943.= c=0D=0A@@ -38,6 +38,9 @@ lp3943_pwm_request_map(struct lp3943_pwm= *lp3943_pwm, int hwpwm)=0D=0A struct lp3943_pwm_map *pwm_map =3D= &lp3943_pwm->pwm_map[hwpwm];=0D=0A int i, offset;=0D=0A =0D=0A+= if (!pdata->pwms[hwpwm])=0D=0A+ return ERR_PTR(-ENODEV);=0D=0A+= =0D=0A pwm_map->output =3D pdata->pwms[hwpwm]->output;=0D=0A pw= m_map->num_outputs =3D pdata->pwms[hwpwm]->num_outputs;=0D=0A =0D=0A= -- =0D=0A2.46.2.windows.1=0D=0A