Messages in this thread | | | Subject | Re: [PATCH] HID: hid-lg4ff: Fix uninit-value set_autocenter_default | From | Phong Tran <> | Date | Tue, 19 Nov 2019 20:29:49 +0700 |
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On 11/18/19 4:43 PM, Benjamin Tissoires wrote: > On Tue, Nov 5, 2019 at 3:18 PM Phong Tran <tranmanphong@gmail.com> wrote: >> >> syzbot found a problem using of uinit pointer in >> lg4ff_set_autocenter_default(). >> >> Reported-by: syzbot+1234691fec1b8ceba8b1@syzkaller.appspotmail.com >> >> Tested by syzbot: >> >> https://groups.google.com/d/msg/syzkaller-bugs/ApnMLW6sfKE/Qq0bIHGEAQAJ > > This seems weird to me: > > the syzbot link above is about `hid_get_drvdata(hid)`, and, as I read > it, the possibility that hid might not have an initialized value. >
In the dashboard [1] shows BUG: KMSAN: uninit-value in dev_get_drvdata include/linux/device.h:1388 [inline] BUG: KMSAN: uninit-value in hid_get_drvdata include/linux/hid.h:628 [inline] BUG: KMSAN: uninit-value in lg4ff_set_autocenter_default+0x23a/0xa20 drivers/hid/hid-lg4ff.c:477 base on that I did the initialization the pointer in the patch.
> Here you are changing the initialized values of value, entry and > drv_data, all 3 are never used before their first assignment. > > I have a feeling this particular syzbot check has already been fixed > upstream by d9d4b1e46d95 "HID: Fix assumption that devices have > inputs". >
I think the commit d9d4b1 fixed this report [2] by syzbot.
[1] https://syzkaller.appspot.com/bug?extid=1234691fec1b8ceba8b1 [2] https://syzkaller.appspot.com/bug?extid=403741a091bf41d4ae79
regards, Phong. > Cheers, > Benjamin > >> >> Signed-off-by: Phong Tran <tranmanphong@gmail.com> >> --- >> drivers/hid/hid-lg4ff.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c >> index 5e6a0cef2a06..44dfd08b0c32 100644 >> --- a/drivers/hid/hid-lg4ff.c >> +++ b/drivers/hid/hid-lg4ff.c >> @@ -468,10 +468,10 @@ static int lg4ff_play(struct input_dev *dev, void *data, struct ff_effect *effec >> static void lg4ff_set_autocenter_default(struct input_dev *dev, u16 magnitude) >> { >> struct hid_device *hid = input_get_drvdata(dev); >> - s32 *value; >> + s32 *value = NULL; >> u32 expand_a, expand_b; >> - struct lg4ff_device_entry *entry; >> - struct lg_drv_data *drv_data; >> + struct lg4ff_device_entry *entry = NULL; >> + struct lg_drv_data *drv_data = NULL; >> unsigned long flags; >> >> drv_data = hid_get_drvdata(hid); >> -- >> 2.20.1 >> >
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