6.6-stable review patch. If anyone has any objections, please let me know.
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From: Edward Adam Davis eadavis@qq.com
commit 73fb3b92da84637e3817580fa205d48065924e15 upstream.
syzbot reported a uninit-value in cxusb_i2c_xfer. [1]
Only when the write operation of usb_bulk_msg() in dvb_usb_generic_rw() succeeds and rlen is greater than 0, the read operation of usb_bulk_msg() will be executed to read rlen bytes of data from the dvb device into the rbuf.
In this case, although rlen is 1, the write operation failed which resulted in the dvb read operation not being executed, and ultimately variable i was not initialized.
[1] BUG: KMSAN: uninit-value in cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline] BUG: KMSAN: uninit-value in cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196 cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline] cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196 __i2c_transfer+0xe25/0x3150 drivers/i2c/i2c-core-base.c:-1 i2c_transfer+0x317/0x4a0 drivers/i2c/i2c-core-base.c:2315 i2c_transfer_buffer_flags+0x125/0x1e0 drivers/i2c/i2c-core-base.c:2343 i2c_master_send include/linux/i2c.h:109 [inline] i2cdev_write+0x210/0x280 drivers/i2c/i2c-dev.c:183 do_loop_readv_writev fs/read_write.c:848 [inline] vfs_writev+0x963/0x14e0 fs/read_write.c:1057 do_writev+0x247/0x5c0 fs/read_write.c:1101 __do_sys_writev fs/read_write.c:1169 [inline] __se_sys_writev fs/read_write.c:1166 [inline] __x64_sys_writev+0x98/0xe0 fs/read_write.c:1166 x64_sys_call+0x2229/0x3c80 arch/x86/include/generated/asm/syscalls_64.h:21 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Reported-by: syzbot+526bd95c0ec629993bf3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=526bd95c0ec629993bf3 Tested-by: syzbot+526bd95c0ec629993bf3@syzkaller.appspotmail.com Fixes: 22c6d93a7310 ("[PATCH] dvb: usb: support Medion hybrid USB2.0 DVB-T/analogue box") Cc: stable@vger.kernel.org Signed-off-by: Edward Adam Davis eadavis@qq.com Signed-off-by: Hans Verkuil hverkuil@xs4all.nl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/usb/dvb-usb/cxusb.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/media/usb/dvb-usb/cxusb.c +++ b/drivers/media/usb/dvb-usb/cxusb.c @@ -119,9 +119,8 @@ static void cxusb_gpio_tuner(struct dvb_
o[0] = GPIO_TUNER; o[1] = onoff; - cxusb_ctrl_msg(d, CMD_GPIO_WRITE, o, 2, &i, 1);
- if (i != 0x01) + if (!cxusb_ctrl_msg(d, CMD_GPIO_WRITE, o, 2, &i, 1) && i != 0x01) dev_info(&d->udev->dev, "gpio_write failed.\n");
st->gpio_write_state[GPIO_TUNER] = onoff;