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media: usb: msi2500: Fix a possible null-pointer dereference in msi2500_stop_streaming()

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In msi2500_stop_streaming(), there is an if statement on line 870 to
check whether dev->udev is NULL:
    if (dev->udev)

When dev->udev is NULL, it is used on line 877:
    msi2500_ctrl_msg(dev, CMD_STOP_STREAMING, 0)
        usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), ...)

Thus, a possible null-pointer dereference may occur.

To fix this bug, dev->udev is checked before calling msi2500_ctrl_msg().

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Jia-Ju Bai 2019-07-29 12:14:44 +02:00 committed by Mauro Carvalho Chehab
parent bf9d46f751
commit 3ec7fdc583
1 changed files with 1 additions and 1 deletions
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2
drivers/media/usb/msi2500/msi2500.c
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@ -867,7 +867,7 @@ static void msi2500_stop_streaming(struct vb2_queue *vq)
/* according to tests, at least 700us delay is required */
msleep(20);
if (!msi2500_ctrl_msg(dev, CMD_STOP_STREAMING, 0)) {
if (dev->udev && !msi2500_ctrl_msg(dev, CMD_STOP_STREAMING, 0)) {
/* sleep USB IF / ADC */
msi2500_ctrl_msg(dev, CMD_WREG, 0x01000003);
}