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[65.112.8.24]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6eb3efdbea3sm59157906d6.112.2025.03.25.12.28.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Mar 2025 12:28:53 -0700 (PDT) Date: Tue, 25 Mar 2025 15:28:51 -0400 From: Alan Stern To: Wolfram Sang Cc: syzbot , gregkh@linuxfoundation.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: [PATCH] media: dvb: usb: Fix WARNING in dib0700_i2c_xfer/usb_submit_urb Message-ID: <29db5fdc-13c9-45f0-9183-c80d637725c6@rowland.harvard.edu> References: <6bb3b80b-a808-4992-8666-535ed9a5c980@rowland.harvard.edu> <67e2fed5.050a0220.a7ebc.0053.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <67e2fed5.050a0220.a7ebc.0053.GAE@google.com> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The syzbot fuzzer reported a WARNING related to the dib0700 dvb-usb driver: usb 1-1: BOGUS control dir, pipe 80000f80 doesn't match bRequestType c0 WARNING: CPU: 1 PID: 5901 at drivers/usb/core/urb.c:413 usb_submit_urb+0x11= d9/0x18c0 drivers/usb/core/urb.c:411 ... Call Trace: usb_start_wait_urb+0x113/0x520 drivers/usb/core/message.c:59 usb_internal_control_msg drivers/usb/core/message.c:103 [inline] usb_control_msg+0x2b1/0x4c0 drivers/usb/core/message.c:154 dib0700_ctrl_rd drivers/media/usb/dvb-usb/dib0700_core.c:95 [inline] dib0700_i2c_xfer_legacy drivers/media/usb/dvb-usb/dib0700_core.c:315 [inli= ne] dib0700_i2c_xfer+0xc53/0x1060 drivers/media/usb/dvb-usb/dib0700_core.c:361 __i2c_transfer+0x866/0x2220 i2c_transfer+0x271/0x3b0 drivers/i2c/i2c-core-base.c:2315 i2cdev_ioctl_rdwr+0x452/0x710 drivers/i2c/i2c-dev.c:306 i2cdev_ioctl+0x759/0x9f0 drivers/i2c/i2c-dev.c:467 vfs_ioctl fs/ioctl.c:51 [inline] Evidently the fuzzer submitted an I2C transfer containing a length-0 read message. The dib0700 driver translated this more or less literally into a length-0 USB read request. But the USB protocol does not allow reads to have length 0; all length-0 transfers are considered to be writes. Hence the WARNING above. Fix the problem by adding the I2C_AQ_NO_ZERO_LEN_READ adapter quirk flag to all the USB I2C adapter devices managed by dvb-usb-i2c.c, following Wolfram Sang's suggestion. This tells the I2C core not to allow length-0 read messages. Reported-by: syzbot+c38e5e60d0041a99dbf5@syzkaller.appspotmail.com Tested-by: syzbot+c38e5e60d0041a99dbf5@syzkaller.appspotmail.com Suggested-by: Wolfram Sang Signed-off-by: Alan Stern Link: https://lore.kernel.org/linux-usb/67e1a1f5.050a0220.a7ebc.0029.GAE@go= ogle.com/ --- Index: usb-devel/drivers/media/usb/dvb-usb/dvb-usb-i2c.c =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --- usb-devel.orig/drivers/media/usb/dvb-usb/dvb-usb-i2c.c +++ usb-devel/drivers/media/usb/dvb-usb/dvb-usb-i2c.c @@ -10,6 +10,9 @@ =20 int dvb_usb_i2c_init(struct dvb_usb_device *d) { + static const struct i2c_adapter_quirks i2c_usb_quirks =3D { + .flags =3D I2C_AQ_NO_ZERO_LEN_READ, + }; int ret =3D 0; =20 if (!(d->props.caps & DVB_USB_IS_AN_I2C_ADAPTER)) @@ -24,6 +27,7 @@ int dvb_usb_i2c_init(struct dvb_usb_devi strscpy(d->i2c_adap.name, d->desc->name, sizeof(d->i2c_adap.name)); d->i2c_adap.algo =3D d->props.i2c_algo; d->i2c_adap.algo_data =3D NULL; + d->i2c_adap.quirks =3D &i2c_usb_quirks; d->i2c_adap.dev.parent =3D &d->udev->dev; =20 i2c_set_adapdata(&d->i2c_adap, d);