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 9337038424D; Tue, 14 Apr 2026 23:58:09 +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=1776211089; cv=none; b=s9Ha/BOxnujKYIe9KQFdhcuq/SM7JUI2IU1PbpzTPAclMbRrAzprO7BP+iocJNYZuqyv2xeM908TjtI7c4xpaSGrxK1sE2nEgBEAuCrOI7zZTIlu05Qk/Vu+pBA9kVn+U/rINLFvBWFHSMAOsdi1Pu4cqDqjXv2QJ2c7xgss2Lc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776211089; c=relaxed/simple; bh=Ncf1TM3KGCc69Qo8ck7pIPJKQUTkRyFmU/ifvTZXZUo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MCvZgHqi5yqYo0qlI3O61UdchG08Ph0CQv4ge+s4JgGqAuC4qceEvAJGkfZ0wO+pd9c+IW5A2njZnZHy5CnXnruaGoTXNmfXOEHvtQPJIB+LSb33qfNFnrGsWgJ2/AemQ6RwrNg/nIdgdpfdS4IkHMkbnVood3ICI3rizOBnQ3I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=teW2CwnQ; 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="teW2CwnQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD438C19425; Tue, 14 Apr 2026 23:58:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776211089; bh=Ncf1TM3KGCc69Qo8ck7pIPJKQUTkRyFmU/ifvTZXZUo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=teW2CwnQRyZwGMj8dvwPkxhtKLKEq1Z+PeDJS19fuE8Nqb+GxwIw9JtwTblNDOzw2 c0rK26r9Qfaz8aW3xu2ozXEmVrRRtt1yxFOhP6Myi804ymw02tybDOoYVmNKGzKKu2 53H1pgXqGeNgXlgMUtQoWhfMZMF1fFWGT2gMsERtqCSEz8ycpGW6tTWFnbAK8bVTVo /wUMllVPO+FOzp9Ql7BTEhi8d05lk3dMeuYXcMiYelYu1MWPc+Zycrgf1kl65UjuiP qqwDgwJ2N10MRPIQgDUczTPDX1TmGjjbNkfHlJobJBN8lzRgRf3Uwvh4pbRTcrp02M 5h450u+gUohCA== Date: Wed, 15 Apr 2026 02:58:05 +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 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". BR, Jarkko