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 16B6231714F; Wed, 15 Apr 2026 12:08:37 +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=1776254918; cv=none; b=V7AKm0Sxe1jLpq6F/DkXzd2tmgg2ctkt6s29y5Tq6vEIkJayKV7KytWm6tsmzOgIgO18tnhCrS92cVRqySgDGfcuOM9MarcpjQLop4UYz9RSWPMCRqrBhrXOPw+eFYhUV+0LZnFOfbhcRZvYfY+x5xYrWMFpapE7lVQkmyVgxq0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776254918; c=relaxed/simple; bh=uykFcHYs5XbFbRSMsJKgZxNwKQCnwgz6lqEF9ZKrZ7A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jOidQNKV1yyvpVEdqX0dyXgth2nSj5cN1li4Mn1aPiw5s7AyLLgqmRuICWeNLZ3OP3oEDwt8mJOgH062TkbEhZmD+jihPqWx6OQE+Jj7FajvVB9RxQt+GpooDuotC8a4Kk9LK0EAmguXG8ZPZZHHV0iPDBnJ3pL3DQlzG+OaUss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iUv526Qi; 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="iUv526Qi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E7D9C19424; Wed, 15 Apr 2026 12:08:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776254917; bh=uykFcHYs5XbFbRSMsJKgZxNwKQCnwgz6lqEF9ZKrZ7A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iUv526QiHFL9Xp9EvuhOxHOtAnjQzg6fk5HyKW0bR/QRzckXI2cr1Nn6ZN1squea1 ak6hfr4s2AK+pXAaFpvmNUV96EHPDYUrC1wn+iDCzZQWeWdv0xPKuC+H1SkCtPsyIq 4Hyx1aViSG7ypNoYR45odIPoqmlA8lfyGyVchptrn9Iu0InlTjxxKOO07dvdb5yZUT yEqfrWSfRGQ1ENaxHRgsJGDUC9fVr34ZERv4NOUF+Wa6oRsUWpD4ANjZcSHGgeQ4al cWsAHZyktQARomACoNMLB7Vcc206FvVDYMAE9WkwrnxjxMOeZ4dG3zsuzhoLKnXjS2 tXZqt+7ZKWaeA== Date: Wed, 15 Apr 2026 15:08:33 +0300 From: Jarkko Sakkinen To: Thorsten Blum Cc: David Howells , Kees Cook , "Gustavo A. R. Silva" , keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH net-next 2/2] KEYS: annotate struct user_key_payload with __counted_by Message-ID: References: <20260406175810.1018681-3-thorsten.blum@linux.dev> <20260406175810.1018681-4-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Apr 15, 2026 at 11:40:26AM +0200, Thorsten Blum wrote: > On Wed, Apr 15, 2026 at 02:58:05AM +0300, Jarkko Sakkinen wrote: > > On Wed, Apr 08, 2026 at 02:21:19PM +0200, Thorsten Blum wrote: > > > On Wed, Apr 08, 2026 at 12:02:25PM +0300, Jarkko Sakkinen wrote: > > > > On Mon, Apr 06, 2026 at 07:58:10PM +0200, Thorsten Blum wrote: > > > > > Add the __counted_by() compiler attribute to the flexible array member > > > > > 'data' to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > > > > > CONFIG_FORTIFY_SOURCE. > > > > > > > > > > Signed-off-by: Thorsten Blum > > > > > --- > > > > > include/keys/user-type.h | 3 ++- > > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/include/keys/user-type.h b/include/keys/user-type.h > > > > > index 386c31432789..2305991f4fcd 100644 > > > > > --- a/include/keys/user-type.h > > > > > +++ b/include/keys/user-type.h > > > > > @@ -27,7 +27,8 @@ > > > > > struct user_key_payload { > > > > > struct rcu_head rcu; /* RCU destructor */ > > > > > unsigned short datalen; /* length of this data */ > > > > > - char data[] __aligned(__alignof__(u64)); /* actual data */ > > > > > + char data[] /* actual data */ > > > > > + __aligned(__alignof__(u64)) __counted_by(datalen); > > > > > }; > > > > > > > > > > extern struct key_type key_type_user; > > > > > > > > You don't provide any evidence of any improvement. > > > > > > It's a proactive hardening change to help avoid future mistakes. > > > > > > The __counted_by() annotation makes the bounds visible to the compiler > > > and at runtime so that future ->data accesses can be checked against > > > ->datalen. > > > > > > The current code is correct regarding ->data accesses and doesn't > > > require any changes. > > > > OK I'll buy that but send +1 version: > > > > ~/work/kernel.org/jarkko/linux-tpmdd next > > ❯ git am -3 20260406_thorsten_blum_keys_dns_drop_unused_upayload_data_nul_terminator.mbx > > Applying: keys, dns: drop unused upayload->data NUL terminator > > error: sha1 information is lacking or useless (net/dns_resolver/dns_key.c). > > error: could not build fake ancestor > > Patch failed at 0001 keys, dns: drop unused upayload->data NUL terminator > > hint: Use 'git am --show-current-patch=diff' to see the failed patch > > When you have resolved this problem, run "git am --continue". > > If you prefer to skip this patch, run "git am --skip" instead. > > To restore the original branch and stop patching, run "git am --abort". > > AFAICT, linux-tpmdd/next is missing this change: > > https://lore.kernel.org/all/20260226214930.785423-3-thorsten.blum@linux.dev/ By pratical means, that is lacking any proper commit message. BR, Jarkko