Re: [PATCH] isdn/gigaset: check endpoint null in gigaset_probe
Hi Phong,
Phong Tran schreef op za 27-07-2019 om 08:56 [+0700]:
> On 7/26/19 9:22 PM, Paul Bolle wrote:
> > Phong Tran schreef op vr 26-07-2019 om 20:35 [+0700]:
> > > 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 = >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.
Looking at this again, I note the code is taking the address of a struct
usb_endpoint_descriptor that's stored somewhere in memory. That address can't
be NULL, can it?
So I haven't even looked at the fuzzer's report here, but I don't see how this
patch could help. It only adds dead code. Am I missing something and should I
drink even more coffee this Saturday morning?
> > > 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,
> > >
> > 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?
It's just that your patch arrived while I was busy doing my last ever test of
the gigaset driver. So please don't expect me to put much time in this report
(see
https://lwn.net/ml/linux-kernel/20190726220541.28783-1-pebolle%40tiscali.nl/
).
Thanks,
Paul Bolle
Re: [PATCH] isdn/gigaset: check endpoint null in gigaset_probe
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+35b1c403a14f5c89e...@syzkaller.appspotmail.com
Tested by syzbot:
https://groups.google.com/d/msg/syzkaller-bugs/wnHG8eRNWEA/Qn2HhjNdBgAJ
Signed-off-by: Phong Tran
---
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 = >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 = >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
Re: [PATCH] isdn/gigaset: check endpoint null in gigaset_probe
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+35b1c403a14f5c89e...@syzkaller.appspotmail.com
> Tested by syzbot:
> https://groups.google.com/d/msg/syzkaller-bugs/wnHG8eRNWEA/Qn2HhjNdBgAJ
>
> Signed-off-by: Phong Tran
> ---
> drivers/isdn/gigaset/usb-gigaset.c | 9 +
This is now drivers/staging/isdn/gigaset/usb-gigaset.c.
> 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 = >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?
> 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 = >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.
Thanks,
Paul Bolle
[PATCH] isdn/gigaset: check endpoint null in gigaset_probe
This fixed the potential reference NULL pointer while using variable
endpoint.
Reported-by: syzbot+35b1c403a14f5c89e...@syzkaller.appspotmail.com
Tested by syzbot:
https://groups.google.com/d/msg/syzkaller-bugs/wnHG8eRNWEA/Qn2HhjNdBgAJ
Signed-off-by: Phong Tran
---
drivers/isdn/gigaset/usb-gigaset.c | 9 +
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 = >endpoint[0].desc;
+if (!endpoint) {
+ dev_err(cs->dev, "Couldn't get control endpoint\n");
+ return -ENODEV;
+ }
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 = >endpoint[1].desc;
+if (!endpoint) {
+ dev_err(cs->dev, "Endpoint not available\n");
+ retval = -ENODEV;
+ goto error;
+ }
ucs->busy = 0;
--
2.20.1
