From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 30FC274D0C for ; Tue, 22 Jun 2021 16:42:04 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 206EA29AD2 for ; Tue, 22 Jun 2021 16:42:04 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 7049F29AC4 for ; Tue, 22 Jun 2021 16:42:00 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 3DD3C457EA for ; Tue, 22 Jun 2021 16:42:00 +0200 (CEST) Message-ID: <5f4ba4d0-8092-0096-5b10-7f02d50fc865@proxmox.com> Date: Tue, 22 Jun 2021 16:41:50 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:90.0) Gecko/20100101 Thunderbird/90.0 Content-Language: en-US To: Proxmox VE development discussion , Stoiko Ivanov References: <20210622142824.18773-1-s.ivanov@proxmox.com> From: Thomas Lamprecht In-Reply-To: <20210622142824.18773-1-s.ivanov@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.695 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [proxmox.com, tools.pm] Subject: Re: [pve-devel] [PATCH common] run_command: untaint end of buffer X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Jun 2021 14:42:04 -0000 On 22.06.21 16:28, Stoiko Ivanov wrote: > The performance improvements added in > cb9db10c1a9855cf40ff13e81f9dd97d6a9b2698 changed the output handling > to not remove the taintedness (see perlsec (1)) of the complete output > anymore. > > This results in a few bugs which show up every now and then, and are > usually quite tedious to hunt down - usually they only occur when > run via GUI (since pveproxy/pvedaemon run in taint-mode, whereas our > CLI utilities usually do not) - see for example pve-storage commit > 609f117ff24d2cff6b155e1d4b1175ceebe5bd7b > > or more recently the report in our community-forum: > https://forum.proxmox.com/threads/cannot-clone-vm-or-move-disk-with-more-than-13-snapshots.89628/ > (the magic number of 13 snapshots is the point where the output of > `qemu-img info --output=json` grows to more than 4k) > > Given the doubtful security benefit of having to untaint output, only > if it does not end in new-line or if it is longer than 4k (we read > the output in 4k chunks) simply untaint the output unconditionally. > > Tested with the reproducer from the forum-thread > this long message nowhere talks about what the actual issue is, can we rather fix that in the clone call? > Signed-off-by: Stoiko Ivanov > --- > Huge thanks to Dominik who pointed me in the right direction, after I > spend far more time than I'm proud to admit in the JSON::XS source, > perlsec(1), perlguts(1) and the surprisingly unhelpful output of > debugperl -Du > > src/PVE/Tools.pm | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/src/PVE/Tools.pm b/src/PVE/Tools.pm > index 8946e93..eb140ae 100644 > --- a/src/PVE/Tools.pm > +++ b/src/PVE/Tools.pm > @@ -516,7 +516,7 @@ sub run_command { > &$outfunc($line) if $outfunc; > &$logfunc($line) if $logfunc; > } > - $outlog .= $buf; > + ($outlog) .= ($buf =~ /(.*)/); #untaint > }; > my $err = $@; > if ($err) { > @@ -537,7 +537,7 @@ sub run_command { > &$errfunc($line) if $errfunc; > &$logfunc($line) if $logfunc; > } > - $errlog .= $buf; > + ($errlog) .= ($buf =~ /(.*)/); #untaint > }; > my $err = $@; > if ($err) { >