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Miller" , Andreas Larsson , Ingo Molnar , Thomas Gleixner , Lars Kotthoff , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org Cc: linmq006@gmail.com, stable@vger.kernel.org Subject: [PATCH] sparc/led: prevent buffer underflow on zero-length write Date: Thu, 30 Oct 2025 15:21:53 +0800 Message-Id: <20251030072156.30656-1-linmq006@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) 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" Fix out-of-bounds access in led_proc_write() when count is 0. Accessing buf[count - 1] with count=3D0 reads/writes buf[-1]. Check for count=3D=3D0 and return -EINVAL early to fix this. Found via static analysis and code review. Fixes: ee1858d3122d ("[SPARC]: Add sun4m LED driver.") Cc: stable@vger.kernel.org Signed-off-by: Miaoqian Lin --- arch/sparc/kernel/led.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/sparc/kernel/led.c b/arch/sparc/kernel/led.c index f4fb82b019bb..aa0ca0d8d0e2 100644 --- a/arch/sparc/kernel/led.c +++ b/arch/sparc/kernel/led.c @@ -70,6 +70,9 @@ static ssize_t led_proc_write(struct file *file, const ch= ar __user *buffer, { char *buf =3D NULL; =20 + if (count =3D=3D 0) + return -EINVAL; + if (count > LED_MAX_LENGTH) count =3D LED_MAX_LENGTH; =20 --=20 2.39.5 (Apple Git-154)