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[77.7.122.14]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49e60946249sm316140715e9.0.2026.09.13.23.25.46 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 13 Sep 2026 23:25:46 -0700 (PDT) From: Karl Mehltretter To: Eddie James Cc: Karl Mehltretter , Ninad Palsule , Joel Stanley , linux-fsi@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH] fsi: i2cr-scom: Return -EFAULT on usercopy failures Date: Mon, 14 Sep 2026 08:24:26 +0200 Message-Id: <20260914062426.14140-1-kmehltretter@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" copy_to_user() and copy_from_user() return the number of bytes that were not copied. i2cr_scom_read() and i2cr_scom_write() return that value directly, so a usercopy fault is reported as a successful short I/O. Return -EFAULT when either copy fails. A temporary KUnit test called i2cr_scom_write() with an invalid user pointer. The unmodified kernel returned 8. With this change it returned -EFAULT. Both versions were booted under QEMU. Fixes: c0b34bed0bbf ("fsi: Add I2C Responder SCOM driver") Assisted-by: LLM Signed-off-by: Karl Mehltretter --- drivers/fsi/i2cr-scom.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/fsi/i2cr-scom.c b/drivers/fsi/i2cr-scom.c index 83b3c03..7edd3e5 100644 --- a/drivers/fsi/i2cr-scom.c +++ b/drivers/fsi/i2cr-scom.c @@ -46,7 +46,7 @@ static ssize_t i2cr_scom_read(struct file *filep, char __= user *buf, size_t len, =20 ret =3D copy_to_user(buf, &data, len); if (ret) - return ret; + return -EFAULT; =20 return len; } @@ -63,7 +63,7 @@ static ssize_t i2cr_scom_write(struct file *filep, const = char __user *buf, size_ =20 ret =3D copy_from_user(&data, buf, len); if (ret) - return ret; + return -EFAULT; =20 ret =3D fsi_master_i2cr_write(scom->i2cr, (u32)*offset, data); if (ret) base-commit: 22098763a10d9c1340827fcf6edab66f153b27f0 --=20 2.53.0