From 71e83e1b1f42fdf7c0b971620a16380ba5d672fa Mon Sep 17 00:00:00 2001 From: Dominik Csapak Date: Wed, 21 Apr 2021 12:24:57 +0200 Subject: [PATCH] tape/changer/sg_pt_changer: read whole descriptor size for each entry Some changer seem to append more data than we expect, but correctly annotates that size in the subheader. For each descriptor entry, read as much as the size given in the subheader (or until the end of the reader), else our position in the reader is wrong for the next entry, and we will parse incorrect data. Signed-off-by: Dominik Csapak --- src/tape/changer/sg_pt_changer.rs | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/src/tape/changer/sg_pt_changer.rs b/src/tape/changer/sg_pt_changer.rs index 785fc9ce..31c38576 100644 --- a/src/tape/changer/sg_pt_changer.rs +++ b/src/tape/changer/sg_pt_changer.rs @@ -593,6 +593,8 @@ fn decode_element_status_page( break; } + let len_before = reader.len(); + match subhead.element_type_code { 1 => { let desc: TrasnsportDescriptor = unsafe { reader.read_be_value()? }; @@ -693,6 +695,19 @@ 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)?; + } } }