Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755963AbYH3U3i (ORCPT ); Sat, 30 Aug 2008 16:29:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753847AbYH3U3b (ORCPT ); Sat, 30 Aug 2008 16:29:31 -0400 Received: from qb-out-0506.google.com ([72.14.204.232]:13000 "EHLO qb-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752929AbYH3U3a (ORCPT ); Sat, 30 Aug 2008 16:29:30 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=Hmkio7BoFdwbQ2mkZpepgRxPTzzIWFJBz9CVEWXkFY/eXRfUyDweT5Ruc0JQfC37vj 2lNpUAdQRlEwMUzHdJ5CEzvvoKvjezDhs9Sc8bX7HMDxF+OAh8neioi3ry6B8PhVGFbQ MEurQXmUCuRnFwNWyTsrm+9BLbWpqeEsPbZmQ= Date: Sun, 31 Aug 2008 00:29:28 +0400 From: Cyrill Gorcunov To: Vegard Nossum Cc: Tom Tucker , Neil Brown , Chuck Lever , Greg Banks , "J. Bruce Fields" , linux-kernel@vger.kernel.org Subject: Re: buffer overflow in /proc/sys/sunrpc/transports Message-ID: <20080830202928.GB3659@lenovo> References: <20080830184422.GA9598@localhost.localdomain> <20080830190642.GC7611@lenovo> <19f34abd0808301242j63d357f5h7afd3eff796a4cf0@mail.gmail.com> <20080830195622.GH7611@lenovo> <19f34abd0808301259s385844efx13cd5b02d083da77@mail.gmail.com> <20080830200423.GI7611@lenovo> <19f34abd0808301313v640a47fbl7bc61fd35e7cf4d5@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <19f34abd0808301313v640a47fbl7bc61fd35e7cf4d5@mail.gmail.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3805 Lines: 95 [Vegard Nossum - Sat, Aug 30, 2008 at 10:13:23PM +0200] | On Sat, Aug 30, 2008 at 10:04 PM, Cyrill Gorcunov wrote: | > [Vegard Nossum - Sat, Aug 30, 2008 at 09:59:38PM +0200] | > | On Sat, Aug 30, 2008 at 9:56 PM, Cyrill Gorcunov wrote: | > | > | BTW, look at this: | > | > | | > | > | $ od -A x -t x1z /proc/sys/sunrpc/transports | > | > | 000000 74 63 70 20 31 30 34 38 35 37 36 0a 75 64 70 20 >tcp 1048576.udp < | > | > | 000010 33 32 37 36 38 0a 00 00 00 00 00 00 00 00 00 00 >32768...........< | > | > | 000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >................< | > | > | * | > | > | 0003e0 00 00 00 00 00 00 00 00 00 00 >..........< | > | > | 0003ea | > | > | | > | > | ...and: | > | > | | > | > | $ strace -e trace=read cat /proc/sys/sunrpc/transports > /dev/null | > | > | read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@G\316E4\0\0\0"..., | > | > | 512) = 512 | > | > | read(3, "tcp 1048576\nudp 32768\n\0\0\0\0\0\0\0\0\0\0"..., 4096) = 4074 | > | > | read(3, "", 4096) = 0 | > | > | | > | > | ...why does it have a huge return value? The output is only about 40 | > | > | bytes... why add all the \0? Would your patch also fix this? | > | > | > | > I think it's from strace side - it pass 4096 zero'ed buffer. | > | | > | "cat" passed buffer of size 4096, yes. But read() still returned 4074. | > | It should have returned 38 or so. | > | | > | > At least I don't see additional issues from kernel side in buffer | > | > filling - except from svc_print_xprts() which walk over list. | > | > But I think sunpc guys should know details :) | > | > Will send short-fix patch soon :) | > | | > | It looks like it's returning (sizeof(buffer) - x) where it really | > | should be returning x. Maybe it's this one that should be different? | > | | > | *lenp -= len; | > | | > | > yes, but this is just a side effect, if we fix main error - it should | > resolve this problem too. Did you try the fix I sent a few msgs ago? | > (I don't have sunrpc on my machine) | | Sorry, I did it now :-) | | $ uname -a | Linux grianne 2.6.27-rc5-00006-gbef69ea-dirty #4 SMP PREEMPT Sat | Aug 30 22:07:18 CEST 2008 i686 i686 i386 GNU/Linux | | $ strace -e trace=read cat /proc/sys/sunrpc/transports > /dev/null | read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320 | \265\0004\0\0\0"..., 512) = 512 | read(3, "tcp 1048576\nudp 32768\n\0\0\0\0\0\0\0\0\0\0"..., 4096) = 4074 | read(3, "", 4096) = 0 | | So that problem seems to remain. | | | Vegard Vegard, are you sure you test it with this patch (a bit updated)? | | -- | "The animistic metaphor of the bug that maliciously sneaked in while | the programmer was not looking is intellectually dishonest as it | disguises that the error is the programmer's own creation." | -- E. W. Dijkstra, EWD1036 | - Cyrill - --- Index: linux-2.6.git/net/sunrpc/sysctl.c =================================================================== --- linux-2.6.git.orig/net/sunrpc/sysctl.c 2008-07-20 11:40:14.000000000 +0400 +++ linux-2.6.git/net/sunrpc/sysctl.c 2008-08-31 00:19:42.000000000 +0400 @@ -69,9 +69,10 @@ static int proc_do_xprt(ctl_table *table return -EINVAL; else { len = svc_print_xprts(tmpbuf, sizeof(tmpbuf)); + if (*lenp < len) + len = *lenp; if (!access_ok(VERIFY_WRITE, buffer, len)) return -EFAULT; - if (__copy_to_user(buffer, tmpbuf, len)) return -EFAULT; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/