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 CDB2A687CE for ; Thu, 22 Jul 2021 11:27:01 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id C4D9BF3D9 for ; Thu, 22 Jul 2021 11:26:31 +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 0C0E7F3CB for ; Thu, 22 Jul 2021 11:26:31 +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 CA4B3420FC for ; Thu, 22 Jul 2021 11:26:30 +0200 (CEST) From: Dominik Csapak To: pbs-devel@lists.proxmox.com Date: Thu, 22 Jul 2021 11:26:29 +0200 Message-Id: <20210722092630.2227801-1-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 0.532 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 v4 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 09:27:01 -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 slice the descriptor data into equal sized chunks of the correct size, then we do not have care bout the len and empty checks anymore this also makes the code to read the rest of the page obsolete, since the next descriptor is on the correct offset anyway Signed-off-by: Dominik Csapak --- src/tape/changer/sg_pt_changer.rs | 31 ++----------------------------- 1 file changed, 2 insertions(+), 29 deletions(-) diff --git a/src/tape/changer/sg_pt_changer.rs b/src/tape/changer/sg_pt_changer.rs index a15d8192..098c10d8 100644 --- a/src/tape/changer/sg_pt_changer.rs +++ b/src/tape/changer/sg_pt_changer.rs @@ -651,17 +651,9 @@ fn decode_element_status_page( } let descr_data = reader.read_exact_allocated(len)?; - let mut reader = &descr_data[..]; - loop { - if reader.is_empty() { - break; - } - if reader.len() < (subhead.descriptor_length as usize) { - break; - } - - let len_before = reader.len(); + for descriptor in descr_data.chunks_exact(subhead.descriptor_length as usize) { + let mut reader = &descriptor[..]; match subhead.element_type_code { 1 => { @@ -672,9 +664,6 @@ 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 +680,6 @@ 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 { @@ -763,19 +749,6 @@ 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)?; - } } } -- 2.30.2