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CVE-2012-1162 / -1163: Incorrect loop construct and numeric overflow in libzip
From: Timo Warns <Warns () Pre-Sense DE>
Date: Wed, 21 Mar 2012 08:37:00 +0100
The following two issues in libzip have been handled via distros () vs openwall org. Distros and the libzip developers were informed on 2012-03-12. An update of libzip has become available on 2012-03-20, the appointed coordinated release date. The PHP and zipruby developers have been informed before 2012-03-16, but have not released updates yet. libzip (version <= 0.10) has two vulnerabilities that may lead to a heap overflow or an information leak via corrupted zip files. PHP (versions 5.4.0 and <= 5.3.10) and the Ruby binding zipruby (version <= 0.3.6) are also affected as they include copies of affected libzip versions. * CVE-2012-1162 libzip (version <= 0.10) uses an incorrect loop construct, which can result in a heap overflow on corrupted zip files. On opening a zip file with zip_open, libzip reads in the number of directory entries in the function _zip_readcdir in zip_open.c: (192) /* number of cdir-entries */ (193) nentry = _zip_read2(&cdp); Subsequently, memory for directory entries is allocated via _zip_cdir_new (in zip_dirent.c) based on the number of directory entries: (104) if ((cd->entry=(struct zip_dirent *)malloc(sizeof(*(cd->entry))*nentry)) If the number of directories in the zip file is set to 0, 0 bytes of memory are allocated. _zip_readcdir finishes with reading in the directory entries in a posttest do-while loop: (260) do { (261) if ((_zip_dirent_read(cd->entry+i, fp, bufp, &left, 0, error)) < 0) { ... (277) } while (i<cd->nentry && left > 0); If cd->entry points to 0 bytes of allocated memory, _zip_dirent writes beyond the allocated memory. * CVE-2012-1163 libzip (version <= 0.10) has a numeric overflow condition, which, for example, results in improper restrictions of operations within the bounds of a memory buffer (e.g., allowing information leaks). On opening a zip file with zip_open, libzip reads in the size and the offset of the central directory structure in the function _zip_readcdir in zip_open.c: (198) cd->size = _zip_read4(&cdp); (199) cd->offset = _zip_read4(&cdp); libzip performs a consistency check on these values, but does not anticipate an integer overflow: (203) if (cd->offset+cd->size > buf_offset + (eocd-buf)) { On an integer overflow, libzip continues to handle the zip file, which, for example, can result in improper restriction of operations within the bounds of a memory buffer. Cheers, Timo
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- CVE-2012-1162 / -1163: Incorrect loop construct and numeric overflow in libzip Timo Warns (Mar 21)