From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A808BC433FF for ; Tue, 6 Aug 2019 12:51:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7BF8220C01 for ; Tue, 6 Aug 2019 12:51:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="eMzlPd4E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731909AbfHFMvD (ORCPT ); Tue, 6 Aug 2019 08:51:03 -0400 Received: from mail-pl1-f177.google.com ([209.85.214.177]:37180 "EHLO mail-pl1-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731104AbfHFMvC (ORCPT ); Tue, 6 Aug 2019 08:51:02 -0400 Received: by mail-pl1-f177.google.com with SMTP id b3so37875078plr.4 for ; Tue, 06 Aug 2019 05:51:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=o/Of7gnFjNlYZMBf78waHqPimHfP3RU+CQjMntOpVvM=; b=eMzlPd4EBCnV+s/Ums9HwV+WL/jKoe1IKYlCEww1YgLdJ6/QiSxZeRizXYpixzAUxG 92GzDVmn4VtHpwVQ9/WVESJFdBIKqCR8rYd5UietWb4T/ss+gam86/P2HkyZmjhYodnS 5OnIoAM+Xvb66xOs1Gt2vB8vAxJpkyk/hdnnO5rDsM8Mj+0evcH+QOqX7Rr1KjHSMuj1 kbJ+xBj7d1HgpwcJSrKKQzQ478XUAxmZiSCaraq/7vVfdDv6BzyCga9yJ6Z3sdIa6LEB ZsE5Sc45brqqHENg4ZU57PkT2L+/t9FdwerTRCRcydjOFllj0fTHlJCH/VvRysP58GVu Mo9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=o/Of7gnFjNlYZMBf78waHqPimHfP3RU+CQjMntOpVvM=; b=iTbGtLinUFHesRBEbV0aIpl8ZMsPEB2F5kXpen1Y2INkxQqvxQms61IsTKgJOCbgjH DelFNcPwPp8Qj2zBNMHJMtr4fbvpxcIuHz41NXng5+MyLFNHgT354IIWVoU66PJ6r3yh IARkKHmCIhw26WesfzO83H8mAF8vIh+WBFV3vPt2lkW16ixG+UBcSsjBnnJ0/k9h6Feb RonQfYAYyaUTdoQ7c2REI5xKMXuDkwr9stgQ1Hu3RAxUJmFvffZGl5Mq0LQiTUwbJ89w t6j60CdTNhMIh/61gGt+PX7oxR7or8cQiccrWCg+gowWu4mn2e4ZovYjleZCv9qr1JdU TLpg== X-Gm-Message-State: APjAAAWkDDqBIPG0j2mUjO9/VKnsWkwDGjA9pZ06C102d2QIK3BCl7oE KW/Uog8GKkNu0O9i0jpV5UPJcAznsCAZ6+sqqeo+EA== X-Google-Smtp-Source: APXvYqzihCoaFQUPrkbjQsOtc0LFfMF/L5IY24117UvLqAZecCOTru0wu7N7UYzsH6gvCzbMwvpY85OkRbx6duvMjkA= X-Received: by 2002:a17:902:6a87:: with SMTP id n7mr2992398plk.336.1565095861407; Tue, 06 Aug 2019 05:51:01 -0700 (PDT) MIME-Version: 1.0 References: <1565095011.8136.20.camel@suse.com> In-Reply-To: <1565095011.8136.20.camel@suse.com> From: Andrey Konovalov Date: Tue, 6 Aug 2019 14:50:50 +0200 Message-ID: Subject: Re: KASAN: use-after-free Read in device_release_driver_internal To: Oliver Neukum Cc: Alan Stern , syzkaller-bugs , syzbot , LKML , USB list Content-Type: multipart/mixed; boundary="000000000000dd87f8058f7246cd" Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org --000000000000dd87f8058f7246cd Content-Type: text/plain; charset="UTF-8" On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum wrote: > > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern: > > > > I think this must be caused by an unbalanced refcount. That is, > > something must drop one more reference to the device than it takes. > > That would explain why the invalid access occurs inside a single > > bus_remove_device() call, between the klist_del() and > > device_release_driver(). > > > > The kernel log indicates that the device was probed by rndis_wlan, > > rndis_host, and cdc_acm, all of which got errors because of the > > device's bogus descriptors. Probably one of them is messing up the > > refcount. > > Hi, > > you made me look at cdc-acm. I suspect > > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail") > > is buggy decrementing the refcount on the interface in destroy() > even before the refcount is increased. > > Unfortunately I cannot tell from the bug report how many and which > interfaces the emulated test device has. Hence it is unclear to me, > when exactly probe() would fail cdc-acm. > > If you agree. I am attaching a putative fix. Let's see if it fixes the issue. #syz fix: https://github.com/google/kasan.git 6a3599ce > > Regards > Oliver --000000000000dd87f8058f7246cd Content-Type: text/x-patch; charset="US-ASCII"; name="0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch" Content-Disposition: attachment; filename="0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch" Content-Transfer-Encoding: base64 Content-ID: X-Attachment-Id: f_jyztngtt0 RnJvbSA2YjMxOTA0ZTZjZjc1Zjg5NDQxZTMwOGI5ZTQyOGExZGU3NzI4ZmQ4IE1vbiBTZXAgMTcg MDA6MDA6MDAgMjAwMQpGcm9tOiBPbGl2ZXIgTmV1a3VtIDxvbmV1a3VtQHN1c2UuY29tPgpEYXRl OiBUdWUsIDYgQXVnIDIwMTkgMTQ6MzQ6MjcgKzAyMDAKU3ViamVjdDogW1BBVENIXSB1c2I6IGNk Yy1hY206IG1ha2Ugc3VyZSBhIHJlZmNvdW50IGlzIHRha2VuIGVhcmx5IGVub3VnaAoKZGVzdHJv eSgpIHdpbGwgZGVjcmVtZW50IHRoZSByZWZjb3VudCBvbiB0aGUgaW50ZXJmYWNlLCBzbyB0aGF0 Cml0IG5lZWRzIHRvIGJlIHRha2VuIHNvIGVhcmx5IHRoYXQgaXQgbmV2ZXIgdW5kZXJjb3VudHMu CgpTaWduZWQtb2ZmLWJ5OiBPbGl2ZXIgTmV1a3VtIDxvbmV1a3VtQHN1c2UuY29tPgotLS0KIGRy aXZlcnMvdXNiL2NsYXNzL2NkYy1hY20uYyB8IDEyICsrKysrKystLS0tLQogMSBmaWxlIGNoYW5n ZWQsIDcgaW5zZXJ0aW9ucygrKSwgNSBkZWxldGlvbnMoLSkKCmRpZmYgLS1naXQgYS9kcml2ZXJz L3VzYi9jbGFzcy9jZGMtYWNtLmMgYi9kcml2ZXJzL3VzYi9jbGFzcy9jZGMtYWNtLmMKaW5kZXgg MTgzYjQxNzUzYzk4Li4yOGUzZGU3NzVhZGEgMTAwNjQ0Ci0tLSBhL2RyaXZlcnMvdXNiL2NsYXNz L2NkYy1hY20uYworKysgYi9kcml2ZXJzL3VzYi9jbGFzcy9jZGMtYWNtLmMKQEAgLTEzMDEsMTAg KzEzMDEsNiBAQCBzdGF0aWMgaW50IGFjbV9wcm9iZShzdHJ1Y3QgdXNiX2ludGVyZmFjZSAqaW50 ZiwKIAl0dHlfcG9ydF9pbml0KCZhY20tPnBvcnQpOwogCWFjbS0+cG9ydC5vcHMgPSAmYWNtX3Bv cnRfb3BzOwogCi0JbWlub3IgPSBhY21fYWxsb2NfbWlub3IoYWNtKTsKLQlpZiAobWlub3IgPCAw KQotCQlnb3RvIGFsbG9jX2ZhaWwxOwotCiAJY3RybHNpemUgPSB1c2JfZW5kcG9pbnRfbWF4cChl cGN0cmwpOwogCXJlYWRzaXplID0gdXNiX2VuZHBvaW50X21heHAoZXByZWFkKSAqCiAJCQkJKHF1 aXJrcyA9PSBTSU5HTEVfUlhfVVJCID8gMSA6IDIpOwpAQCAtMTMxMiw2ICsxMzA4LDEzIEBAIHN0 YXRpYyBpbnQgYWNtX3Byb2JlKHN0cnVjdCB1c2JfaW50ZXJmYWNlICppbnRmLAogCWFjbS0+d3Jp dGVzaXplID0gdXNiX2VuZHBvaW50X21heHAoZXB3cml0ZSkgKiAyMDsKIAlhY20tPmNvbnRyb2wg PSBjb250cm9sX2ludGVyZmFjZTsKIAlhY20tPmRhdGEgPSBkYXRhX2ludGVyZmFjZTsKKworCXVz Yl9nZXRfaW50ZihhY20tPmNvbnRyb2wpOyAvKiB1bmRvbmUgaW4gZGVzdHJveSgpICovCisKKwlt aW5vciA9IGFjbV9hbGxvY19taW5vcihhY20pOworCWlmIChtaW5vciA8IDApCisJCWdvdG8gYWxs b2NfZmFpbDE7CisKIAlhY20tPm1pbm9yID0gbWlub3I7CiAJYWNtLT5kZXYgPSB1c2JfZGV2Owog CWlmIChoLnVzYl9jZGNfYWNtX2Rlc2NyaXB0b3IpCkBAIC0xNDU4LDcgKzE0NjEsNiBAQCBzdGF0 aWMgaW50IGFjbV9wcm9iZShzdHJ1Y3QgdXNiX2ludGVyZmFjZSAqaW50ZiwKIAl1c2JfZHJpdmVy X2NsYWltX2ludGVyZmFjZSgmYWNtX2RyaXZlciwgZGF0YV9pbnRlcmZhY2UsIGFjbSk7CiAJdXNi X3NldF9pbnRmZGF0YShkYXRhX2ludGVyZmFjZSwgYWNtKTsKIAotCXVzYl9nZXRfaW50Zihjb250 cm9sX2ludGVyZmFjZSk7CiAJdHR5X2RldiA9IHR0eV9wb3J0X3JlZ2lzdGVyX2RldmljZSgmYWNt LT5wb3J0LCBhY21fdHR5X2RyaXZlciwgbWlub3IsCiAJCQkmY29udHJvbF9pbnRlcmZhY2UtPmRl dik7CiAJaWYgKElTX0VSUih0dHlfZGV2KSkgewotLSAKMi4xNi40Cgo= --000000000000dd87f8058f7246cd--