From nobody Sat Feb 7 15:22:12 2026 Received: from mail-oa1-f71.google.com (mail-oa1-f71.google.com [209.85.160.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00E59221DB3 for ; Mon, 26 Jan 2026 05:19:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.71 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769404786; cv=none; b=GytvjboOky5YGvAk9K06FPXELkec6bpgQ2T8cytT0IrcN8vTwnkUAOQY1S/VUrWrpna/Ty0CLtQqb5zrAhLSZHwUy1gWBDkdPIKKrEZ9mvEAeYvGf1Cb13iLD6fDNS3xx3skj0f8SnrNMH2+PPmHoR2E1TBGJi6w2OjFDd1syKs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769404786; c=relaxed/simple; bh=iLQOrJujC/PbZesmrTW26oDNgRhNhAlgRVGaAB+rIW0=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=PO27AvEiJ2moh5w4d0qUVhrGQOSfReTYPYvYg+ZpWk0GOHNzYnOPFltJWbDlwdkuL/a8uZg0pJrMw5wOmn4zX4/9LzJLcLPuAVXHCYkyt2twshSHSlXKw2H9kG0jMnsuTxFvAVMx2F3dBnL8Q5JAQ4oPbyUS7yqHu1xptX3Y/4Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.160.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oa1-f71.google.com with SMTP id 586e51a60fabf-4040acebf22so6260023fac.1 for ; Sun, 25 Jan 2026 21:19:44 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769404784; x=1770009584; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5j2bwEG3SuUyYqzrtsW2PnEiJ73RUL7hYLz8WPaW+Lk=; b=mPWzKEQHKXOsopvc9IP53RJzit8beQp4JbcmF4RUv9ipNuj3w5YH91luqL5pkeSo3E hmpOV0ldp7iNGgSZY8ndKRleDyNSr1Ga9nZwS/zqEiIYyH73mfZAnZpLJT5DTR52YAmx T0xz6MNyoDNNb75hRs2KeEp0K1C7HkfT1rg5pp7C4KOE5+UpktwYzsrGLzLY3unY5ivT 0wJFUridJsI7dbq1wO+rhTxffG+cC8QETewgE3lOntUq2P/SStJ54PKOK+o1XGsJTNPF UZdPEMjzwE6N6NYYOVhl++swHZVm7HnH0wErMX09ixiwKf8lnesl/1ivB4f63CjC9TN7 yc4A== X-Gm-Message-State: AOJu0YxExe0ZZWbL3wx9gZe2NeI67UhZ07e0wmzNrcrAKCUNqfLsY9+o nIUlclmL8r9aiAgmdhRc0mEOzlrqXlcImDJq2AizY6YJBxlxYJsePSz/xCSgyfkVlN/dUxgmaW0 szulyJt0QEU50aT89VKzy88fjO83YgZhSsouu7GubM0kARwuOZ64nPfoiDAY= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:2913:b0:662:ba27:878a with SMTP id 006d021491bc7-662e00f85c7mr1506427eaf.0.1769404783974; Sun, 25 Jan 2026 21:19:43 -0800 (PST) Date: Sun, 25 Jan 2026 21:19:43 -0800 In-Reply-To: <69746a86.050a0220.226181.0003.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6976f96f.050a0220.226181.0011.GAE@google.com> Subject: Forwarded: [PATCH] comedi: dt2815: Add debug logging to diagnose iobase issue From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: [PATCH] comedi: dt2815: Add debug logging to diagnose iobase issue Author: kartikey406@gmail.com #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git= master Add comprehensive debug logging to dt2815_attach() to diagnose the page fault crash reported by syzbot. The crash occurs at line 199 when attempting outb() operation, with a fault at address 0xfffffffffffffff= 0. This debug patch will help determine: - Whether it->options[0] is correctly passed - If dev->iobase is properly set by comedi_request_region() - If dev->iobase value changes during execution - The exact status value that triggers the crash path Once we identify the root cause from the logs, a proper fix will be implemented. Reported-by: syzbot+72f94b474d6e50b71ffc@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=3D72f94b474d6e50b71ffc Signed-off-by: Deepanshu Kartikey --- drivers/comedi/drivers/dt2815.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/comedi/drivers/dt2815.c b/drivers/comedi/drivers/dt281= 5.c index 03ba2fd18a21..8e77c9851110 100644 --- a/drivers/comedi/drivers/dt2815.c +++ b/drivers/comedi/drivers/dt2815.c @@ -144,10 +144,15 @@ static int dt2815_attach(struct comedi_device *dev, s= truct comedi_devconfig *it) const struct comedi_lrange *current_range_type, *voltage_range_type; int ret; =20 + printk(KERN_INFO "dt2815: it->options[0] =3D 0x%lx\n", it->options[0]); + ret =3D comedi_request_region(dev, it->options[0], 0x2); if (ret) return ret; =20 + printk(KERN_INFO "dt2815: after comedi_request_region, dev->iobase =3D 0x= %lx\n", dev->iobase); + + ret =3D comedi_alloc_subdevices(dev, 1); if (ret) return ret; @@ -176,13 +181,18 @@ static int dt2815_attach(struct comedi_device *dev, s= truct comedi_devconfig *it) } =20 /* Init the 2815 */ + printk(KERN_INFO "dt2815: Before first outb, dev->iobase =3D 0x%lx\n", de= v->iobase); outb(0x00, dev->iobase + DT2815_STATUS); + printk(KERN_INFO "dt2815: After first outb\n"); + for (i =3D 0; i < 100; i++) { /* This is incredibly slow (approx 20 ms) */ unsigned int status; =20 usleep_range(1000, 3000); + printk(KERN_INFO "dt2815: Loop iteration %d, dev->iobase =3D 0x%lx\n", i= , dev->iobase); status =3D inb(dev->iobase + DT2815_STATUS); + printk(KERN_INFO "dt2815: status =3D 0x%x\n", status); if (status =3D=3D 4) { unsigned int program; =20 @@ -195,8 +205,11 @@ static int dt2815_attach(struct comedi_device *dev, st= ruct comedi_devconfig *it) dev_dbg(dev->class_dev, "unexpected status 0x%x (@t=3D%d)\n", status, i); - if (status & 0x60) + if (status & 0x60) { + printk(KERN_INFO "dt2815: About to do second outb, dev =3D %px, dev->i= obase =3D 0x%lx\n", dev, dev->iobase); outb(0x00, dev->iobase + DT2815_STATUS); + printk(KERN_INFO "dt2815: After second outb\n"); + } } } =20 --=20 2.43.0