Date: Thu, 09 Feb 2017 14:48:10 +0100 From: Agostino Sarubbo <ago@...too.org> To: oss-security@...ts.openwall.com Subject: zziplib: NULL pointer dereference in zzip_mem_entry_new (memdisk.c) Description: zziplib is an intentionally lightweight library that offers the ability to easily extract data from files archived in a single zip file. A fuzz on it discovered an NULL pointer access. The complete ASan output: # unzzipcat-mem $FILE ==7955==ERROR: AddressSanitizer: SEGV on unknown address 0x00000000001a (pc 0x7fcfc78e3c50 bp 0x7ffdf55d4f70 sp 0x7ffdf55d4e40 T0) ==7955==The signal is caused by a READ memory access. ==7955==Hint: address points to the zero page. #0 0x7fcfc78e3c4f in zzip_mem_entry_new /tmp/portage/dev- libs/zziplib-0.13.62-r1/work/zziplib-0.13.62/zzip/memdisk.c:182:21 #1 0x7fcfc78e3c4f in zzip_mem_disk_load /tmp/portage/dev- libs/zziplib-0.13.62-r1/work/zziplib-0.13.62/zzip/memdisk.c:137 #2 0x7fcfc78e38b7 in zzip_mem_disk_open /tmp/portage/dev- libs/zziplib-0.13.62-r1/work/zziplib-0.13.62/zzip/memdisk.c:89:5 #3 0x50982d in main /tmp/portage/dev-libs/zziplib-0.13.62- r1/work/zziplib-0.13.62/bins/unzzipcat-mem.c:82:12 #4 0x7fcfc6a2361f in __libc_start_main /var/tmp/portage/sys- libs/glibc-2.22-r4/work/glibc-2.22/csu/libc-start.c:289 #5 0x419748 in _init (/usr/bin/unzzipcat-mem+0x419748) AddressSanitizer can not provide additional info. SUMMARY: AddressSanitizer: SEGV /tmp/portage/dev-libs/zziplib-0.13.62- r1/work/zziplib-0.13.62/zzip/memdisk.c:182:21 in zzip_mem_entry_new ==7955==ABORTING also, the undefined behavior sanitizer says about: # unzzipcat-mem $FILE /tmp/portage/dev-libs/zziplib-0.13.62- r1/work/zziplib-0.13.62/zzip/memdisk.c:182:21: runtime error: member access within null pointer of type 'struct zzip_file_header' Affected version: 0.13.62 Fixed version: N/A Commit fix: N/A Credit: This bug was discovered by Agostino Sarubbo of Gentoo. CVE: N/A Reproducer: https://github.com/asarubbo/poc/blob/master/00154-zziplib-nullptr-zzip_mem_entry_new Timeline: 2017-01-17: bug discovered and poked upstream 2017-02-09: blog post about the issue Note: This bug was found with American Fuzzy Lop. Permalink: https://blogs.gentoo.org/ago/2017/02/09/zziplib-null-pointer-dereference-in-zzip_mem_entry_new-memdisk-c -- Agostino Sarubbo Gentoo Linux Developer
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