Re: [syzbot] KASAN: slab-out-of-bounds Read in thrustmaster_probe

[Pavel Skripkin <paskripkin@gmail.com>]

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On 2/20/22 18:27, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    c5d9ae265b10 Merge tag 'for-linus' of git://git.kernel.org..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14ccc65c700000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a78b064590b9f912
> dashboard link: https://syzkaller.appspot.com/bug?extid=35eebd505e97d315d01c
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=175ecbf2700000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=109973f2700000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+35eebd505e97d315d01c@syzkaller.appspotmail.com
> 
> usb 1-1: config 0 interface 0 altsetting 0 endpoint 0x81 has invalid wMaxPacketSize 0
> usb 1-1: New USB device found, idVendor=044f, idProduct=b65d, bcdDevice= 0.40
> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> usb 1-1: config 0 descriptor??
> hid-thrustmaster 0003:044F:B65D.0001: unknown main item tag 0x0
> hid-thrustmaster 0003:044F:B65D.0001: hidraw0: USB HID v0.00 Device [HID 044f:b65d] on usb-dummy_hcd.0-1/input0
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in thrustmaster_interrupts drivers/hid/hid-thrustmaster.c:162 [inline]
> BUG: KASAN: slab-out-of-bounds in thrustmaster_probe+0x8d5/0xb50 drivers/hid/hid-thrustmaster.c:330
> Read of size 1 at addr ffff88807f1a59d2 by task kworker/1:1/35
> 

Looks like missing check for malicious device. Need to check number of 
endpoints before accessing endpoints array


#syz test
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master





With regards,
Pavel Skripkin

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diff --git a/drivers/hid/hid-thrustmaster.c b/drivers/hid/hid-thrustmaster.c
index 03b935ff02d5..244c3aa4d0c3 100644
--- a/drivers/hid/hid-thrustmaster.c
+++ b/drivers/hid/hid-thrustmaster.c
@@ -158,6 +158,11 @@ static void thrustmaster_interrupts(struct hid_device *hdev)
 		return;
 	}
 
+	if (usbif->cur_altsetting->desc.bNumEndpoints < 2) {
+		hid_err(hdev, "Wrong number of endpoints?\n");
+		return;
+	}
+
 	ep = &usbif->cur_altsetting->endpoint[1];
 	b_ep = ep->desc.bEndpointAddress;