From 57a6514a40ebd8a222831bee5aa071e7b3f3e016 Mon Sep 17 00:00:00 2001 From: Pascal Hertleif Date: Tue, 27 Jun 2017 11:23:17 +0200 Subject: [PATCH] Prevent subtract with overflow This changes assumes this only happens when the archive is invalid. Fixes #40 --- src/read.rs | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/read.rs b/src/read.rs index b584eb29..01dc0fa5 100644 --- a/src/read.rs +++ b/src/read.rs @@ -85,7 +85,9 @@ impl ZipArchive // Some zip files have data prepended to them, resulting in the offsets all being too small. Get the amount of // error by comparing the actual file position we found the CDE at with the offset recorded in the CDE. - let archive_offset = cde_start_pos - footer.central_directory_size - footer.central_directory_offset; + let archive_offset = cde_start_pos.checked_sub(footer.central_directory_size) + .and_then(|x| x.checked_sub(footer.central_directory_offset)) + .ok_or(ZipError::InvalidArchive("Invalid central directory size or offset"))?; let directory_start = (footer.central_directory_offset + archive_offset) as u64; let number_of_files = footer.number_of_files_on_this_disk as usize;