From: Willem de Bruijn <willemb@xxxxxxxxxx> One caller of gp8psk_power_ctrl fails to check the return value. Syzbot KMSAN found a use of uninitialized data. This path is also exercised when no such device exists, as in this cloud environment. Argument status is not set if gp8psk_power_ctrl returns early. Tests its return value in this case, too. BUG: KMSAN: uninit-value in gp8psk_power_ctrl+0x33e/0xca0 drivers/media/usb/dvb-usb/gp8psk.c:193 CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: usb_hub_wq hub_event Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x191/0x1f0 lib/dump_stack.c:113 kmsan_report+0x130/0x2a0 mm/kmsan/kmsan.c:622 __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310 gp8psk_power_ctrl+0x33e/0xca0 drivers/media/usb/dvb-usb/gp8psk.c:193 dvb_usb_device_power_ctrl drivers/media/usb/dvb-usb/dvb-usb-init.c:226 [inline] dvb_usb_init drivers/media/usb/dvb-usb/dvb-usb-init.c:160 [inline] dvb_usb_device_init+0x15ad/0x2cc0 drivers/media/usb/dvb-usb/dvb-usb-init.c:277 gp8psk_usb_probe+0xa2/0x190 drivers/media/usb/dvb-usb/gp8psk.c:307 usb_probe_interface+0xd66/0x1320 drivers/usb/core/driver.c:361 really_probe+0xdae/0x1d80 drivers/base/dd.c:513 driver_probe_device+0x1b3/0x4f0 drivers/base/dd.c:671 __device_attach_driver+0x5b8/0x790 drivers/base/dd.c:778 bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:454 __device_attach+0x454/0x730 drivers/base/dd.c:844 device_initial_probe+0x4a/0x60 drivers/base/dd.c:891 bus_probe_device+0x137/0x390 drivers/base/bus.c:514 device_add+0x288d/0x30e0 drivers/base/core.c:2106 usb_set_configuration+0x30dc/0x3750 drivers/usb/core/message.c:2027 generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210 usb_probe_device+0x14c/0x200 drivers/usb/core/driver.c:266 [..snip..] Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: Willem de Bruijn <willemb@xxxxxxxxxx> --- drivers/media/usb/dvb-usb/gp8psk.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/media/usb/dvb-usb/gp8psk.c b/drivers/media/usb/dvb-usb/gp8psk.c index 1282f701f1857..b666644f06d7b 100644 --- a/drivers/media/usb/dvb-usb/gp8psk.c +++ b/drivers/media/usb/dvb-usb/gp8psk.c @@ -184,9 +184,13 @@ static int gp8psk_power_ctrl(struct dvb_usb_device *d, int onoff) { u8 status, buf; int gp_product_id = le16_to_cpu(d->udev->descriptor.idProduct); + int ret; if (onoff) { - gp8psk_usb_in_op(d, GET_8PSK_CONFIG,0,0,&status,1); + ret = gp8psk_usb_in_op(d, GET_8PSK_CONFIG, 0, 0, &status, 1); + if (ret) + return ret; + if (! (status & bm8pskStarted)) { /* started */ if(gp_product_id == USB_PID_GENPIX_SKYWALKER_CW3K) gp8psk_usb_out_op(d, CW3K_INIT, 1, 0, NULL, 0); -- 2.22.0.410.gd8fdbe21b5-goog