From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (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 18259316199 for ; Mon, 2 Mar 2026 09:47:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=82.195.75.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772444860; cv=none; b=BWN4mLXI1J5VeBt/gzH6FMN3qxj5e48eO05i+N9IvEVrt8Y36tVTwkQcqo0+RLoC9utqkTYGbR5eDouItRymuhm9Tt9wrvQ10wjkFRMESo2XCczWE0PNXBfMMBX7iFp1yz6wloOZmCBGCO8BA34fy/sZiFBXT2Fcz6hB1RmFMv0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772444860; c=relaxed/simple; bh=pkfo9xAAmB4lkUPldzmNXbsKuegLh5yXTCET7EO12OI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FHvp7Xxc+h/v8b1xm8XeVaR91BhYHo4RSPj/oD0YoVNL//YwoSgStdk8RQWi25Y02LlCIDgKm+BEZrP5dWGYYqKmAi/4qUm0V8jiU+6Ll5zKvo8mg1IMS0vZu5HrBeXXzY9rWFa9KhSRbdI37zUtMMMgOpAF5MWNoLREHRtQol0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=none smtp.mailfrom=debian.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b=cU0xRUpd; arc=none smtp.client-ip=82.195.75.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=debian.org header.i=@debian.org header.b="cU0xRUpd" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=POGLBn//kxkI+OrMk5uSkSnwSuGPHc4YQGBzV8+pC1U=; b=cU0xRUpduvxnLJho+e5E47fmne I3gL2RunT/bNTPdhrDldNwlsZtOfBgishDZsDtCKAF5W38tjfOD7laAu6qD6Te3/2EYtcL2sz8WO/ cT60Cf/OMHA0/dze/gbcHht08FFPSUm9R8a6ollalXVgJfIIt+WKBaJQjUhl01jh1CHZWBdME7ik8 pPU8779TxwfE/l1C7cHVz+im2a6mS5nbyMeBnWndl3diczUyMUxOYDm0Fh3T/6oWQrfKzUpddOwma BAbNb4jsPhjj55+kjiSCC1lcpZ2IDV/pfB9deH3taLvnvKuxqdPb5QPZpvPaTIrH6k7ste8sfMyTP /RcQ+aLg==; Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1vwzs4-00EJl1-Lm; Mon, 02 Mar 2026 09:47:24 +0000 Date: Mon, 2 Mar 2026 01:47:18 -0800 From: Breno Leitao To: Simon Horman Cc: Jakub Kicinski , davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch 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: X-Debian-User: leitao On Sun, Feb 22, 2026 at 04:13:19PM +0000, Simon Horman wrote: > 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 Thanks for the fix and review while I was out. --breno