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 701EB687BD for ; Thu, 22 Jul 2021 11:05:25 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 6E49BF16F for ; Thu, 22 Jul 2021 11:05:25 +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 A4F80F164 for ; Thu, 22 Jul 2021 11:05:24 +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 7880E424F4 for ; Thu, 22 Jul 2021 11:05:24 +0200 (CEST) From: Dominik Csapak To: pbs-devel@lists.proxmox.com Date: Thu, 22 Jul 2021 11:05:22 +0200 Message-Id: <20210722090523.1999546-1-d.csapak@proxmox.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.535 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 SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: [pbs-devel] [PATCH proxmox-backup v3 1/2] tape: changer: correctly consume data in decode_element_status_page X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Jul 2021 09:05:25 -0000 instead of 'blindly' trusting the changer to deliver the fields written in the specification, trust the length data it returns in the header. we prepare the reader to be exaclty the size of the descriptor given to us by the subheader, and offset the descriptor data by exactly that amount after each one we can drop the reading of the 'reserved' bytes, since we do not need them or the data after this also makes the code to read the rest of the page obsolete, since the we simply start on the correct offset anyway Signed-off-by: Dominik Csapak --- changes from v2: * drop 'sg_pt' from commit subject * drop the 'remaining_size' calculation, instead prepare the reader to be at the right offset src/tape/changer/sg_pt_changer.rs | 29 +++++++---------------------- 1 file changed, 7 insertions(+), 22 deletions(-) diff --git a/src/tape/changer/sg_pt_changer.rs b/src/tape/changer/sg_pt_changer.rs index a15d8192..ddbb5d74 100644 --- a/src/tape/changer/sg_pt_changer.rs +++ b/src/tape/changer/sg_pt_changer.rs @@ -651,17 +651,18 @@ fn decode_element_status_page( } let descr_data = reader.read_exact_allocated(len)?; - let mut reader = &descr_data[..]; + let mut descriptors_to_read = &descr_data[..]; + let descriptor_len = subhead.descriptor_length as usize; loop { - if reader.is_empty() { + if descriptors_to_read.is_empty() { break; } - if reader.len() < (subhead.descriptor_length as usize) { + if descriptors_to_read.len() < descriptor_len { break; } - let len_before = reader.len(); + let mut reader = &descriptors_to_read[..descriptor_len]; match subhead.element_type_code { 1 => { @@ -672,9 +673,6 @@ fn decode_element_status_page( subhead.skip_alternate_volume_tag(&mut reader)?; - let mut reserved = [0u8; 4]; - reader.read_exact(&mut reserved)?; - result.last_element_address = Some(desc.element_address); let status = TransportElementStatus { @@ -691,9 +689,6 @@ fn decode_element_status_page( subhead.skip_alternate_volume_tag(&mut reader)?; - let mut reserved = [0u8; 4]; - reader.read_exact(&mut reserved)?; - result.last_element_address = Some(desc.element_address); if subhead.element_type_code == 3 { @@ -764,18 +759,8 @@ fn decode_element_status_page( code => bail!("got unknown element type code {}", code), } - // we have to consume the whole descriptor size, else - // our position in the reader is not correct - let len_after = reader.len(); - let have_read = len_before - len_after; - let desc_len = subhead.descriptor_length as usize; - if desc_len > have_read { - let mut left_to_read = desc_len - have_read; - if left_to_read > len_after { - left_to_read = len_after; // reader has not enough data? - } - let _ = reader.read_exact_allocated(left_to_read)?; - } + // set position to next descriptor + descriptors_to_read = &descriptors_to_read[descriptor_len..]; } } -- 2.30.2