linux-kernel - Re: [PATCH 2/2] SUNRPC: Optimize 'svc_print

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2e2d1293-c978-3f1d-5a1e-dc43dc2ad06b@wanadoo.fr>
Date:   Thu, 26 Mar 2020 13:19:12 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     linux-kernel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/2] SUNRPC: Optimize 'svc_print_xprts()'

Le 25/03/2020 à 23:53, NeilBrown a écrit :
> Can I suggest something more like this:
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index de3c077733a7..0292f45b70f6 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -115,16 +115,9 @@ int svc_print_xprts(char *buf, int maxlen)
>   	buf[0] = '\0';
>   
>   	spin_lock(&svc_xprt_class_lock);
> -	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
> -		int slen;
> -
> -		sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
> -		slen = strlen(tmpstr);
> -		if (len + slen > maxlen)
> -			break;
> -		len += slen;
> -		strcat(buf, tmpstr);
> -	}
> +	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list)
> +		len += scnprintf(buf + len, maxlen - len, "%s %d\n",
> +				 xcl->xcl_name, xcl->xcl_max_payload);
>   	spin_unlock(&svc_xprt_class_lock);
>   
>   	return len;
>
> NeilBrown

Hi,

this was what I suggested in the patch:
     ---
     This patch should have no functional change.
     We could go further, use scnprintf and write directly in the 
destination
     buffer. However, this could lead to a truncated last line.
     ---

And Chuck Lever confirmed that:
     That's exactly what this function is trying to avoid. As part of any
     change in this area, it would be good to replace the current block
     comment before this function with a Doxygen-format comment that
     documents that goal.

So, I will only send a V2 based on comments already received.

CJ