Messages in this thread | | | Subject | Re: [PATCH] isdn/gigaset: check endpoint null in gigaset_probe | From | Phong Tran <> | Date | Sat, 27 Jul 2019 08:56:02 +0700 |
| |
On 7/26/19 9:22 PM, Paul Bolle wrote: > Phong Tran schreef op vr 26-07-2019 om 20:35 [+0700]: >> This fixed the potential reference NULL pointer while using variable >> endpoint. >> >> Reported-by: syzbot+35b1c403a14f5c89eba7@syzkaller.appspotmail.com >> Tested by syzbot: >> https://groups.google.com/d/msg/syzkaller-bugs/wnHG8eRNWEA/Qn2HhjNdBgAJ >> >> Signed-off-by: Phong Tran <tranmanphong@gmail.com> >> --- >> drivers/isdn/gigaset/usb-gigaset.c | 9 +++++++++ > > This is now drivers/staging/isdn/gigaset/usb-gigaset.c.
this patch was created base on branch kasan/usb-fuzzer-usb-testing-2019.07.11 [1] I did not notice about the driver was moved to staging.
> >> 1 file changed, 9 insertions(+) >> >> diff --git a/drivers/isdn/gigaset/usb-gigaset.c b/drivers/isdn/gigaset/usb-gigaset.c >> index 1b9b43659bdf..2e011f3db59e 100644 >> --- a/drivers/isdn/gigaset/usb-gigaset.c >> +++ b/drivers/isdn/gigaset/usb-gigaset.c >> @@ -703,6 +703,10 @@ static int gigaset_probe(struct usb_interface *interface, >> usb_set_intfdata(interface, cs); >> >> endpoint = &hostif->endpoint[0].desc; >> + if (!endpoint) { >> + dev_err(cs->dev, "Couldn't get control endpoint\n"); >> + return -ENODEV; >> + } > > When can this happen? Is this one of those bugs that one can only trigger with > a specially crafted (evil) usb device? >
Yes, in my understanding, this only happens with random test of syzbot.
>> buffer_size = le16_to_cpu(endpoint->wMaxPacketSize); >> ucs->bulk_out_size = buffer_size; >> @@ -722,6 +726,11 @@ static int gigaset_probe(struct usb_interface *interface, >> } >> >> endpoint = &hostif->endpoint[1].desc; >> + if (!endpoint) { >> + dev_err(cs->dev, "Endpoint not available\n"); >> + retval = -ENODEV; >> + goto error; >> + } >> >> ucs->busy = 0; >> > > Please note that I'm very close to getting cut off from the ISDN network, so > the chances of being able to testi this on a live system are getting small. >
This bug can be invalid now. Do you agree? There is an instruction to report invalid bug to syzbot [2].
> Thanks, > > > Paul Bolle >
[1] https://github.com/google/kasan/commits/usb-fuzzer-usb-testing-2019.07.11 [2] https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
Thanks, Phong
| |