diff mbox series

HID: usbhid: fix recurrent out-of-bounds bug in usbhid_parse()

Message ID 20240524120112.28076-1-n.zhandarovich@fintech.ru (mailing list archive)
State New
Delegated to: Jiri Kosina
Headers show
Series HID: usbhid: fix recurrent out-of-bounds bug in usbhid_parse() | expand

Commit Message

Nikita Zhandarovich May 24, 2024, 12:01 p.m. UTC
Syzbot reports [1] a reemerging out-of-bounds bug regarding hid
descriptors possibly having incorrect bNumDescriptors values in
usbhid_parse().

Build on the previous fix in "HID: usbhid: fix out-of-bounds bug"
and run a sanity-check ensuring that number of descriptors doesn't
exceed the size of desc[] in struct hid_descriptor.

[1] Syzbot report:
Link: https://syzkaller.appspot.com/bug?extid=c52569baf0c843f35495

UBSAN: array-index-out-of-bounds in drivers/hid/usbhid/hid-core.c:1024:7
index 1 is out of range for type 'struct hid_class_descriptor[1]'
CPU: 0 PID: 8 Comm: kworker/0:1 Not tainted 6.9.0-rc6-syzkaller-00290-gb9158815de52 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:429
 usbhid_parse+0x5a7/0xc80 drivers/hid/usbhid/hid-core.c:1024
 hid_add_device+0x132/0x520 drivers/hid/hid-core.c:2790
 usbhid_probe+0xb38/0xea0 drivers/hid/usbhid/hid-core.c:1429
 usb_probe_interface+0x645/0xbb0 drivers/usb/core/driver.c:399
 really_probe+0x2b8/0xad0 drivers/base/dd.c:656
 __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:798
 driver_probe_device+0x50/0x430 drivers/base/dd.c:828
 __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:956
 bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:457
 __device_attach+0x333/0x520 drivers/base/dd.c:1028
 bus_probe_device+0x189/0x260 drivers/base/bus.c:532
 device_add+0x8ff/0xca0 drivers/base/core.c:3720
 usb_set_configuration+0x1976/0x1fb0 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0x88/0x140 drivers/usb/core/generic.c:254
 usb_probe_device+0x1b8/0x380 drivers/usb/core/driver.c:294

Reported-and-tested-by: syzbot+c52569baf0c843f35495@syzkaller.appspotmail.com
Fixes: f043bfc98c19 ("HID: usbhid: fix out-of-bounds bug")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
---
 drivers/hid/usbhid/hid-core.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Jiri Kosina June 4, 2024, 8:15 a.m. UTC | #1
On Fri, 24 May 2024, Nikita Zhandarovich wrote:

> Syzbot reports [1] a reemerging out-of-bounds bug regarding hid
> descriptors possibly having incorrect bNumDescriptors values in
> usbhid_parse().
> 
> Build on the previous fix in "HID: usbhid: fix out-of-bounds bug"
> and run a sanity-check ensuring that number of descriptors doesn't
> exceed the size of desc[] in struct hid_descriptor.
> 
> [1] Syzbot report:
> Link: https://syzkaller.appspot.com/bug?extid=c52569baf0c843f35495
> 
> UBSAN: array-index-out-of-bounds in drivers/hid/usbhid/hid-core.c:1024:7
> index 1 is out of range for type 'struct hid_class_descriptor[1]'
> CPU: 0 PID: 8 Comm: kworker/0:1 Not tainted 6.9.0-rc6-syzkaller-00290-gb9158815de52 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Workqueue: usb_hub_wq hub_event
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  ubsan_epilogue lib/ubsan.c:231 [inline]
>  __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:429
>  usbhid_parse+0x5a7/0xc80 drivers/hid/usbhid/hid-core.c:1024
>  hid_add_device+0x132/0x520 drivers/hid/hid-core.c:2790
>  usbhid_probe+0xb38/0xea0 drivers/hid/usbhid/hid-core.c:1429
>  usb_probe_interface+0x645/0xbb0 drivers/usb/core/driver.c:399
>  really_probe+0x2b8/0xad0 drivers/base/dd.c:656
>  __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:798
>  driver_probe_device+0x50/0x430 drivers/base/dd.c:828
>  __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:956
>  bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:457
>  __device_attach+0x333/0x520 drivers/base/dd.c:1028
>  bus_probe_device+0x189/0x260 drivers/base/bus.c:532
>  device_add+0x8ff/0xca0 drivers/base/core.c:3720
>  usb_set_configuration+0x1976/0x1fb0 drivers/usb/core/message.c:2210
>  usb_generic_driver_probe+0x88/0x140 drivers/usb/core/generic.c:254
>  usb_probe_device+0x1b8/0x380 drivers/usb/core/driver.c:294
> 
> Reported-and-tested-by: syzbot+c52569baf0c843f35495@syzkaller.appspotmail.com
> Fixes: f043bfc98c19 ("HID: usbhid: fix out-of-bounds bug")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>

Applied, thanks.
Kees Cook June 4, 2024, 2:11 p.m. UTC | #2
On June 4, 2024 1:15:35 AM PDT, Jiri Kosina <jikos@kernel.org> wrote:
>On Fri, 24 May 2024, Nikita Zhandarovich wrote:
>
>> Syzbot reports [1] a reemerging out-of-bounds bug regarding hid
>> descriptors possibly having incorrect bNumDescriptors values in
>> usbhid_parse().
>> 
>> Build on the previous fix in "HID: usbhid: fix out-of-bounds bug"
>> and run a sanity-check ensuring that number of descriptors doesn't
>> exceed the size of desc[] in struct hid_descriptor.
>> 
>> [1] Syzbot report:
>> Link: https://syzkaller.appspot.com/bug?extid=c52569baf0c843f35495
>> 
>> UBSAN: array-index-out-of-bounds in drivers/hid/usbhid/hid-core.c:1024:7
>> index 1 is out of range for type 'struct hid_class_descriptor[1]'
>> CPU: 0 PID: 8 Comm: kworker/0:1 Not tainted 6.9.0-rc6-syzkaller-00290-gb9158815de52 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
>> Workqueue: usb_hub_wq hub_event
>> Call Trace:
>>  <TASK>
>>  __dump_stack lib/dump_stack.c:88 [inline]
>>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>>  ubsan_epilogue lib/ubsan.c:231 [inline]
>>  __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:429
>>  usbhid_parse+0x5a7/0xc80 drivers/hid/usbhid/hid-core.c:1024
>>  hid_add_device+0x132/0x520 drivers/hid/hid-core.c:2790
>>  usbhid_probe+0xb38/0xea0 drivers/hid/usbhid/hid-core.c:1429
>>  usb_probe_interface+0x645/0xbb0 drivers/usb/core/driver.c:399
>>  really_probe+0x2b8/0xad0 drivers/base/dd.c:656
>>  __driver_probe_device+0x1a2/0x390 drivers/base/dd.c:798
>>  driver_probe_device+0x50/0x430 drivers/base/dd.c:828
>>  __device_attach_driver+0x2d6/0x530 drivers/base/dd.c:956
>>  bus_for_each_drv+0x24e/0x2e0 drivers/base/bus.c:457
>>  __device_attach+0x333/0x520 drivers/base/dd.c:1028
>>  bus_probe_device+0x189/0x260 drivers/base/bus.c:532
>>  device_add+0x8ff/0xca0 drivers/base/core.c:3720
>>  usb_set_configuration+0x1976/0x1fb0 drivers/usb/core/message.c:2210
>>  usb_generic_driver_probe+0x88/0x140 drivers/usb/core/generic.c:254
>>  usb_probe_device+0x1b8/0x380 drivers/usb/core/driver.c:294
>> 
>> Reported-and-tested-by: syzbot+c52569baf0c843f35495@syzkaller.appspotmail.com
>> Fixes: f043bfc98c19 ("HID: usbhid: fix out-of-bounds bug")
>> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>
>Applied, thanks.

This isn't the right solution. The problem is that hid_class_descriptor is a flexible array but was sized as a single element fake flexible array: 

struct hid_descriptor {
	   __u8  bLength;
	   __u8  bDescriptorType;
	   __le16 bcdHID;
	   __u8  bCountryCode;
	   __u8  bNumDescriptors;

	   struct hid_class_descriptor desc[1];
} __attribute__ ((packed));

This likely needs to be: 

struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);

And then check for any sizeof() uses of the struct that might have changed.
Jiri Kosina June 4, 2024, 2:15 p.m. UTC | #3
On Tue, 4 Jun 2024, Kees Cook wrote:

> This isn't the right solution. The problem is that hid_class_descriptor 
> is a flexible array but was sized as a single element fake flexible 
> array:
> 
> struct hid_descriptor {
> 	   __u8  bLength;
> 	   __u8  bDescriptorType;
> 	   __le16 bcdHID;
> 	   __u8  bCountryCode;
> 	   __u8  bNumDescriptors;
> 
> 	   struct hid_class_descriptor desc[1];
> } __attribute__ ((packed));
> 
> This likely needs to be: 
> 
> struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);
> 
> And then check for any sizeof() uses of the struct that might have changed.

Ah, you are of course right, not sure what I was thinking. Thanks a lot 
for catching my brainfart.

I am dropping the patch for now; Nikita, will you please send a refreshed 
one?
Nikita Zhandarovich June 4, 2024, 5:09 p.m. UTC | #4
Hi,

On 6/4/24 07:15, Jiri Kosina wrote:
> On Tue, 4 Jun 2024, Kees Cook wrote:
> 
>> This isn't the right solution. The problem is that hid_class_descriptor 
>> is a flexible array but was sized as a single element fake flexible 
>> array:
>>
>> struct hid_descriptor {
>> 	   __u8  bLength;
>> 	   __u8  bDescriptorType;
>> 	   __le16 bcdHID;
>> 	   __u8  bCountryCode;
>> 	   __u8  bNumDescriptors;
>>
>> 	   struct hid_class_descriptor desc[1];
>> } __attribute__ ((packed));
>>
>> This likely needs to be: 
>>
>> struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);
>>
>> And then check for any sizeof() uses of the struct that might have changed.
> 
> Ah, you are of course right, not sure what I was thinking. Thanks a lot 
> for catching my brainfart.
> 
> I am dropping the patch for now; Nikita, will you please send a refreshed 
> one?
> 

Thanks for catching my mistake.

I'll gladly send a revised version, hoping to do it very soon.

Regards,
Nikita
Kees Cook June 4, 2024, 5:21 p.m. UTC | #5
On Tue, Jun 04, 2024 at 10:09:43AM -0700, Nikita Zhandarovich wrote:
> Hi,
> 
> On 6/4/24 07:15, Jiri Kosina wrote:
> > On Tue, 4 Jun 2024, Kees Cook wrote:
> > 
> >> This isn't the right solution. The problem is that hid_class_descriptor 
> >> is a flexible array but was sized as a single element fake flexible 
> >> array:
> >>
> >> struct hid_descriptor {
> >> 	   __u8  bLength;
> >> 	   __u8  bDescriptorType;
> >> 	   __le16 bcdHID;
> >> 	   __u8  bCountryCode;
> >> 	   __u8  bNumDescriptors;
> >>
> >> 	   struct hid_class_descriptor desc[1];
> >> } __attribute__ ((packed));
> >>
> >> This likely needs to be: 
> >>
> >> struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);
> >>
> >> And then check for any sizeof() uses of the struct that might have changed.
> > 
> > Ah, you are of course right, not sure what I was thinking. Thanks a lot 
> > for catching my brainfart.
> > 
> > I am dropping the patch for now; Nikita, will you please send a refreshed 
> > one?
> > 
> 
> Thanks for catching my mistake.
> 
> I'll gladly send a revised version, hoping to do it very soon.

I spent a little more time looking at this, and I'm not sure I
understand where the actual space for the descriptors comes from?
There's interface->extra that is being parsed, and effectively
hid_descriptor is being mapped into it, but it uses "sizeof(struct
hid_descriptor)" for the limit. Is more than 1 descriptor expected to
work correctly? Or is the limit being ignored? I'm a bit confused by
this code...
Alan Stern June 4, 2024, 5:45 p.m. UTC | #6
On Tue, Jun 04, 2024 at 10:21:15AM -0700, Kees Cook wrote:
> On Tue, Jun 04, 2024 at 10:09:43AM -0700, Nikita Zhandarovich wrote:
> > Hi,
> > 
> > On 6/4/24 07:15, Jiri Kosina wrote:
> > > On Tue, 4 Jun 2024, Kees Cook wrote:
> > > 
> > >> This isn't the right solution. The problem is that hid_class_descriptor 
> > >> is a flexible array but was sized as a single element fake flexible 
> > >> array:
> > >>
> > >> struct hid_descriptor {
> > >> 	   __u8  bLength;
> > >> 	   __u8  bDescriptorType;
> > >> 	   __le16 bcdHID;
> > >> 	   __u8  bCountryCode;
> > >> 	   __u8  bNumDescriptors;
> > >>
> > >> 	   struct hid_class_descriptor desc[1];
> > >> } __attribute__ ((packed));
> > >>
> > >> This likely needs to be: 
> > >>
> > >> struct hid_class_descriptor desc[] __counted_by(bNumDescriptors);
> > >>
> > >> And then check for any sizeof() uses of the struct that might have changed.
> > > 
> > > Ah, you are of course right, not sure what I was thinking. Thanks a lot 
> > > for catching my brainfart.
> > > 
> > > I am dropping the patch for now; Nikita, will you please send a refreshed 
> > > one?
> > > 
> > 
> > Thanks for catching my mistake.
> > 
> > I'll gladly send a revised version, hoping to do it very soon.
> 
> I spent a little more time looking at this, and I'm not sure I
> understand where the actual space for the descriptors comes from?
> There's interface->extra that is being parsed, and effectively
> hid_descriptor is being mapped into it, but it uses "sizeof(struct
> hid_descriptor)" for the limit.

That's a lower limit, not an upper limit.  The hid_descriptor must 
include at least one hid_class_descriptor, but it can include more.
That's what the min_t() calculation of num_descriptors is meant to 
figure out.

>  Is more than 1 descriptor expected to
> work correctly?

More than one hid_class_descriptor -- yes.

>  Or is the limit being ignored? I'm a bit confused by
> this code...

Does this explain it?

Alan Stern
diff mbox series

Patch

diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index a90ed2ceae84..f38a4bd3a20e 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -1020,6 +1020,9 @@  static int usbhid_parse(struct hid_device *hid)
 	num_descriptors = min_t(int, hdesc->bNumDescriptors,
 	       (hdesc->bLength - offset) / sizeof(struct hid_class_descriptor));
 
+	if (num_descriptors > ARRAY_SIZE(hdesc->desc))
+		num_descriptors = ARRAY_SIZE(hdesc->desc);
+
 	for (n = 0; n < num_descriptors; n++)
 		if (hdesc->desc[n].bDescriptorType == HID_DT_REPORT)
 			rsize = le16_to_cpu(hdesc->desc[n].wDescriptorLength);