From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-171.sina.com.cn (smtp153-171.sina.com.cn [61.135.153.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABBE74CA29B for ; Wed, 16 Sep 2026 10:20:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789554036; cv=none; b=dibxo2u/7ekn2gErb9gzwCvf0LM2I/ueNf5bNf1o8K6ouM9PNuVoAakQHzAMNWHwDrKQU8Vms2xzHijQK2BuVjvLHtzHIxb+7hJ9d9TNTPk6r73cH7r4YYn33l5mZKi9BUze5GePtH0ykpK54SR+tptYLMN8HI1PpDHWtc8OV0Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789554036; c=relaxed/simple; bh=LaWqsRsY7lwyGYS9zC4kuEQHn/PDtAfdYiNfTA8uRno=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=vFNaxLZlKOx0zEphYYo30z2Hd1U8tDp+EhoXGC5tfU0KqBvOCEAku2reBAbdq+pneMRaWQik3x0SwH9Jpjp3tyeGWyq35RPpnB4OezAwFv9C8cAxUKad//pxHkyZT5fzUPNczB0qpOyyh5O8foBKNtzR+63ApvXSeuR+Njsk+/w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=GOLQ+Zk+; arc=none smtp.client-ip=61.135.153.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="GOLQ+Zk+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1789554016; bh=LYiYZd2BkCMNuO+KpS0oBAcTyuKwxRkARJdKFXdNRZY=; h=From:Subject:Date:Message-ID; b=GOLQ+Zk+PZBDAAg1bmCuAANN2jre0pJe1EP0sRcu+UZsCwvQX83Bfb16JxjKdgHh7 cgNWpTfshPsFqkflP92EfCZhbl7X8X4ppkKdDwXmAfYkJa+0zaSD8EN8Z1x5v/uAsl oZIscZ8udxKNQMiN6SCUykTrim4vvLfQPj+Zvnvw= X-SMAIL-HELO: lxu-ped-host.. Received: from unknown (HELO lxu-ped-host..)([111.198.231.89]) by sina.com (10.54.253.34) with ESMTP id 6AAA6D3200001432; Wed, 16 Sep 2026 18:19:32 +0800 (CST) X-Sender: eadavis@sina.com X-Auth-ID: eadavis@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=eadavis@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=eadavis@sina.com X-SMAIL-MID: 8922956292237 X-SMAIL-UIID: 380486D655394534ABB8D63D88346873-20260916-181932-1 From: Edward Adam Davis To: gregkh@linuxfoundation.org Cc: dakr@kernel.org, driver-core@lists.linux.dev, eadavis@sina.com, linux-kernel@vger.kernel.org, rafael@kernel.org, syzbot+9a321aea9d851b299486@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] sysfs: prevent writing excessively large files Date: Wed, 16 Sep 2026 18:19:30 +0800 Message-ID: <20260916101930.962961-1-eadavis@sina.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <2026091606-distant-paltry-a3f1@gregkh> References: <2026091606-distant-paltry-a3f1@gregkh> Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Edward Aadm Davis On Wed, 16 Sep 2026 09:17:56 +0200, Greg KH wrote: > > Since atomic_write_len is not configured for sysfs_file_kfops_rw, a large > > file write via sysfs_kf_write() may result in an out-of-bounds read when > > checking for the null terminator of a string element in the kobject_actions > > array within kobject_action_type(), potentially hitting: > > What sysfs file are you hitting this on? Regular sysfs files. > > > > > BUG: KASAN: global-out-of-bounds in kobject_action_type lib/kobject_uevent.c:86 [inline] > > BUG: KASAN: global-out-of-bounds in kobject_synth_uevent+0x79d/0x7d0 lib/kobject_uevent.c:200 > > Read of size 1 at addr ffffffff8d72559f by task syz.0.17/5917 > > Call Trace: > > kobject_action_type lib/kobject_uevent.c:86 [inline] > > kobject_synth_uevent+0x79d/0x7d0 lib/kobject_uevent.c:200 > > bus_uevent_store+0x3d/0x90 drivers/base/bus.c:917 > > bus_attr_store+0x74/0xb0 drivers/base/bus.c:172 > > sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 > > kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 > > new_sync_write fs/read_write.c:595 [inline] > > vfs_write+0x6af/0x1050 fs/read_write.c:687 > > > > Add atomic_write_len for sysfs_file_kfops_rw and sysfs_file_kfops_wo > > properly. > > > > Fixes: f6acf8bb6a40 ("sysfs, kernfs: introduce kernfs_ops") > > What changed to suddenly cause this to show up now if this has been > present for decades? This issue has always existed. It remained undetected simply because the buffer lengths typically passed when writing to `/sys/bus/acpi/uevent` happened to be reasonably appropriate. cheers, Edward