From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta0.migadu.com (out-171.mta0.migadu.com [91.218.175.171]) (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 9B01C2868D for ; Fri, 16 Aug 2024 01:53:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723773187; cv=none; b=FxdfEnIusKh+oTUWFSPBO7a18edBHfqpMgm9OCFJS+qgUB15vxAfS+fmZrzeuE2z1cFP/4ob2A04CVqXV1qMNs6bgdi0I+NLdYrAWt2ZjYEND5isljZ72cico/TN1F6ty0cKQh6gMvW9WEsEAEk6Zph166ylrwEdW+zP8y+apcw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723773187; c=relaxed/simple; bh=tNvSG2qi/Vms8GKiFMc5zZLxko1a99mjyAniXm2u8kI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ULNpx/ZeYnVaTJ8URTYUZTgXZweiQyW9mFw5PveC8z9ablMangGy/xRg5Aay7StRHZ451q8+TFXc3z39K1GN+Gidf2mFmP6l3sfdAWguLyNl8eWF30+UwKFAk3rip7g+ZA6tZtGhBgdbmCgsF1mREcnHXjoUIRcL9i14bH1L58s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=h8qKUBzp; arc=none smtp.client-ip=91.218.175.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="h8qKUBzp" Message-ID: <59d78829-6744-420c-bb8e-f015ca76ecae@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1723773183; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ivala+vb4qzVTVVyFC1nWTgHgxHExBS2dPPK5Wr9eR8=; b=h8qKUBzp2R5/INg4/Be9oikxzV1SnHdFz5FdzWUFhpcp/MZxWpRpsiPiWiVhxyCkoJZFSZ mhC4+pTTXp5Vv6mnpS0GySKUHLQUXhfhC7yqHr7CgriMSH6yqJdJSryXi2Y5DtGooL5FMj qVuwkuy9cnTODv9DCmCqrNc+HpAGg4o= Date: Fri, 16 Aug 2024 09:52:56 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] SUNRPC: Fix -Wformat-truncation warning To: NeilBrown Cc: trondmy@kernel.org, anna@kernel.org, chuck.lever@oracle.com, jlayton@kernel.org, kolga@netapp.com, Dai.Ngo@oracle.com, tom@talpey.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-nfs@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Kunwu Chan References: <> <0282be6f-e8ac-4428-a2ac-1ea6b7c25f4a@linux.dev> <172372194692.6062.4519803974558688969@noble.neil.brown.name> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Kunwu Chan In-Reply-To: <172372194692.6062.4519803974558688969@noble.neil.brown.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Thanks for your reply. On 2024/8/15 19:39, NeilBrown wrote: > On Thu, 15 Aug 2024, Kunwu Chan wrote: >> Thanks for your reply. >> >> On 2024/8/14 18:28, NeilBrown wrote: >>> On Wed, 14 Aug 2024, kunwu.chan@linux.dev wrote: >>>> From: Kunwu Chan >>>> >>>> Increase size of the servername array to avoid truncated output warning. >>>> >>>> net/sunrpc/clnt.c:582:75: error：‘%s’ directive output may be truncated >>>> writing up to 107 bytes into a region of size 48 >>>> [-Werror=format-truncation=] >>>> 582 | snprintf(servername, sizeof(servername), "%s", >>>> | ^~ >>>> >>>> net/sunrpc/clnt.c:582:33: note:‘snprintf’ output >>>> between 1 and 108 bytes into a destination of size 48 >>>> 582 | snprintf(servername, sizeof(servername), "%s", >>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>>> 583 | sun->sun_path); >>>> >>>> Signed-off-by: Kunwu Chan >>>> --- >>>> net/sunrpc/clnt.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>>> index 09f29a95f2bc..874085f3ed50 100644 >>>> --- a/net/sunrpc/clnt.c >>>> +++ b/net/sunrpc/clnt.c >>>> @@ -546,7 +546,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args) >>>> .connect_timeout = args->connect_timeout, >>>> .reconnect_timeout = args->reconnect_timeout, >>>> }; >>>> - char servername[48]; >>>> + char servername[108]; >>> If we choose this approach to removing the warning, then we should use >>> UNIX_PATH_MAX rather than 108. >> My negligence. >>> However the longest server name copied in here will in practice be >>> /var/run/rpcbind.sock >>> >>> so the extra 60 bytes on the stack is wasted ... maybe that doesn't >>> matter. >> I'm thinking  about use a dynamic space alloc method like kasprintf to >> avoid space waste. >>> The string is only used by xprt_create_transport() which requires it to >>> be less than RPC_MAXNETNAMELEN - which is 256. >>> So maybe that would be a better value to use for the array size .... if >>> we assume that stack space isn't a problem. >> Thank you for the detailed explanation. I read the >> xprt_create_transport,  the RPC_MAXNETNAMELEN >> >> is only use to xprt_create_transport . >> >>> What ever number we use, I'd rather it was a defined constant, and not >>> an apparently arbitrary number. >> Whether we could check the sun->sun_path length before using snprintf? >> The array size should smaller >> >> than  the minimum of sun->sun_path and RPC_MAXNETNAMELEN. >> >> Or use the dynamic space allocate method to save space. > I think that dynamically allocating space is not a good idea. It means > you have to handle failure which is just a waste of code. > > I'd suggest simply changing the array to RPC_MAXNETNAMELEN. I'll follow your suggestion and change it in v2. > > NeilBrown > > > >>> Thanks, >>> NeilBrown >>> >>> >>>> struct rpc_clnt *clnt; >>>> int i; >>>> >>>> -- >>>> 2.40.1 >>>> >>>> >> -- >> Thanks, >> Kunwu.Chan >> >> -- Thanks, Kunwu.Chan