Public bug reported: Description:
An error in archive_wstring_append_from_mbs() (archive_string.c) triggers an out-of-bounds read memory access that results into a crash, via a specially crafted archive file. This bug was found using our custom fuzzer. Basic Information: Version of libarchive: libarchive-3.4.0, libarchive-3.4.1dev How you obtained it: build from source libarchive-3.4.0.tar.gz (https://www.libarchive.org/) libarchive-3.4.1dev (https://github.com/libarchive/libarchive) Tested operating system and version: Linux 4.15.0-65-generic x86_64 Tested compilers versions: gcc (version 7.4.0) and clang (version 6.0.0-1ubuntu2) ============ Command to reproduce the bug using valgrind: $ valgrind -v ./bsdtar -t -f crash_file_1 (in the attachment) Output (partial): bsdtar: (null) bsdtar: Error exit delayed from previous errors. HEAP SUMMARY: in use at exit: 0 bytes in 0 blocks total heap usage: 89 allocs, 89 frees, 285,279 bytes allocated All heap blocks were freed -- no leaks are possible ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 0 from 0) 2 errors in context 1 of 1: Invalid read of size 1 at 0x5081825: utf8_internal_loop_single (loop.c:427) by 0x5081825: __gconv_transform_utf8_internal (skeleton.c:563) by 0x5116B12: mbrtowc (mbrtowc.c:86) by 0x14D998: archive_wstring_append_from_mbs (archive_string.c:622) by 0x14E19B: archive_mstring_get_wcs (archive_string.c:3941) by 0x116EF5: archive_entry_pathname_w (archive_entry.c:586) by 0x148297: zip_read_local_file_header (archive_read_support_format_zip.c:1038) by 0x1487EC: archive_read_format_zip_streamable_read_header (archive_read_support_format_zip.c:3083) by 0x11E1AB: _archive_read_next_header2 (archive_read.c:658) by 0x11E2FE: _archive_read_next_header (archive_read.c:696) by 0x112725: read_archive (read.c:260) by 0x112E1F: tar_mode_t (read.c:94) by 0x1114C6: main (bsdtar.c:913) Address 0x5490f47 is 0 bytes after a block of size 167 alloc'd at 0x4C2FA3F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) by 0x4C31D84: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) by 0x14A6E3: archive_string_ensure (archive_string.c:314) by 0x14A78A: archive_string_append (archive_string.c:203) by 0x14DF0D: archive_strncat_l (archive_string.c:1980) by 0x14E4C5: archive_strncpy_l (archive_string.c:1944) by 0x14E4C5: archive_mstring_copy_mbs_len_l (archive_string.c:4153) by 0x147D95: zip_read_local_file_header (archive_read_support_format_zip.c:995) by 0x1487EC: archive_read_format_zip_streamable_read_header (archive_read_support_format_zip.c:3083) by 0x11E1AB: _archive_read_next_header2 (archive_read.c:658) by 0x11E2FE: _archive_read_next_header (archive_read.c:696) by 0x112725: read_archive (read.c:260) by 0x112E1F: tar_mode_t (read.c:94) ERROR SUMMARY: 2 errors from 1 contexts (suppressed: 0 from 0) --------------------------------------------------------------- Possible cause: In archive_wstring_append_from_mbs() (archive_string.c): int archive_wstring_append_from_mbs(struct archive_wstring *dest, const char *p, size_t len){ ... const char *mbs = p; ... while (*mbs && mbs_length > 0) { ... ... r = mbrtowc(wcs, mbs, wcs_length, &shift_state); ... if (r == (size_t)-1 || r == (size_t)-2) { ret_val = -1; if (errno == EILSEQ) { ++mbs; --mbs_length; continue; } else break; } ... ... } } mbrtowc() function is called with the following parameter values: wcs_length = 3, mbs_length = 1, mbs = 0x7ffff6a43ffe "\212". r = mbrtowc(wcs, mbs, wcs_length, &shift_state); Here, "mbs" has a length of 1 byte, while, mbrtowc() tends to read 3 bytes (wcs_length = 3), thus resulting into memory out of bounds read. The program crashes due to memory access violation, which can cause denial of service. The values {wcs_length = 3, mbs_length = 1} are reached, if return value of mbrtowc() is r = -1 or r = -2 in the previous iteration of the while loop. "mbs" pointer increases (++mbs), and "mbs_length" length decreases (--mbs_length), but wcs_length remains constant (3 bytes in this case). ------------------------------------------------ ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: bsdtar 3.1.2-11ubuntu0.16.04.7 ProcVersionSignature: Ubuntu 4.4.0-166.195-generic 4.4.194 Uname: Linux 4.4.0-166-generic x86_64 NonfreeKernelModules: openafs nvidia_uvm nvidia_drm nvidia_modeset nvidia ApportVersion: 2.20.1-0ubuntu2.21 Architecture: amd64 CurrentDesktop: Unity Date: Fri Nov 8 11:58:45 2019 SourcePackage: libarchive UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: libarchive (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug xenial ** Attachment added: "crash_file_1" https://bugs.launchpad.net/bugs/1851867/+attachment/5303891/+files/crash_file_1 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1851867 Title: bsdtar: An error in archive_wstring_append_from_mbs() (archive_string.c) allows out-of-bounds read memory access and subsequently cause a crash To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libarchive/+bug/1851867/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
