From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 BE1FD34FF41 for ; Sun, 22 Feb 2026 16:13:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771776810; cv=none; b=qptzKPLxW36h2Dr4qfvrzZ2H4lzVK5+mxbOzPfKhKZoBbdq7XKrTVnqk7P9Bc9vZidCbklFRHpAtISm57CBeY44Fx4azTHEGMTVIyPGAl4KgebtgFaRJhu6C50kM5eB3O+k+8Hznd+juJLTQSzBYfk0dZlveNmTN75B3n5J+HU4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771776810; c=relaxed/simple; bh=v/6hFuSO8PJHKsZtPakfmI7341eYHwTYsiJnuIJ7aEM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=D5THQYNnfI95NEC+wPVq1acflDJTZvU44H+foj16mZD6AjOFMw6K46qcoDJNO3cs5dp4Y297rbWF3oxtqZW/FjHNi0c1htxoXEGEure8Q8Dn18m+1P415+xYFu51jsm3cv7IU0Z4MX+vEf1fBqB0dDD3fb9r4IrRS+xpWqSaE5M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Swzw9aeL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Swzw9aeL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C78DBC116D0; Sun, 22 Feb 2026 16:13:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771776810; bh=v/6hFuSO8PJHKsZtPakfmI7341eYHwTYsiJnuIJ7aEM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Swzw9aeL/fPjVDloXgfcmXciuhkPrtRCexdsaTuogDoS5wxaPU7uz6WITTo1OwFdR VVxzjT4xKHGVhcVQ9DmXrNkI3keyvx9QyscXuXhygL45XQoYZeGipx5Wrdwn03JEKT XY415XS3jpwK1CknjC3nKFXTzbKVVTYulBQE/QD2zSMNbtI736IVM8c1K0pLqwKCVD +UxmJycvbqRJd1BJr8xoEydhOPFOndXMrBFLp7fZCjIvV/JxWepdCzZgDaY5l2v7Db 0WzEaYbvl3Ttb9c3C9dNJe9QgV9nbDpOLjIrIsuP7x1X5uy1fJezOfxZPtqVg4qR/k 26/HL5EDoY7Fw== Date: Sun, 22 Feb 2026 16:13:19 +0000 From: Simon Horman To: Jakub Kicinski Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, leitao@debian.org Subject: Re: [PATCH net] netconsole: avoid OOB reads, msg is not nul-terminated Message-ID: References: <20260219195021.2099699-1-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260219195021.2099699-1-kuba@kernel.org> On Thu, Feb 19, 2026 at 11:50:21AM -0800, Jakub Kicinski wrote: > msg passed to netconsole from the console subsystem is not guaranteed > to be nul-terminated. Before recent > commit 7eab73b18630 ("netconsole: convert to NBCON console infrastructure") > the message would be placed in printk_shared_pbufs, a static global > buffer, so KASAN had harder time catching OOB accesses. Now we see: > > printk: console [netcon_ext0] enabled > BUG: KASAN: slab-out-of-bounds in string+0x1f7/0x240 > Read of size 1 at addr ffff88813b6d4c00 by task pr/netcon_ext0/594 > > CPU: 65 UID: 0 PID: 594 Comm: pr/netcon_ext0 Not tainted 6.19.0-11754-g4246fd6547c9 > Call Trace: > kasan_report+0xe4/0x120 > string+0x1f7/0x240 > vsnprintf+0x655/0xba0 > scnprintf+0xba/0x120 > netconsole_write+0x3fe/0xa10 > nbcon_emit_next_record+0x46e/0x860 > nbcon_kthread_func+0x623/0x750 > > Allocated by task 1: > nbcon_alloc+0x1ea/0x450 > register_console+0x26b/0xe10 > init_netconsole+0xbb0/0xda0 > > The buggy address belongs to the object at ffff88813b6d4000 > which belongs to the cache kmalloc-4k of size 4096 > The buggy address is located 0 bytes to the right of > allocated 3072-byte region [ffff88813b6d4000, ffff88813b6d4c00) > > Fixes: c62c0a17f9b7 ("netconsole: Append kernel version to message") > Signed-off-by: Jakub Kicinski Reviewed-by: Simon Horman