81dc898df9
When using a padding specifier in the pretty format passed to git-log(1)
we need to calculate the string length in several places. These string
lengths are stored in `int`s though, which means that these can easily
overflow when the input lengths exceeds 2GB. This can ultimately lead to
an out-of-bounds write when these are used in a call to memcpy(3P):
==8340==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7f1ec62f97fe at pc 0x7f2127e5f427 bp 0x7ffd3bd63de0 sp 0x7ffd3bd63588
WRITE of size 1 at 0x7f1ec62f97fe thread T0
#0 0x7f2127e5f426 in __interceptor_memcpy /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827
#1 0x5628e96aa605 in format_and_pad_commit pretty.c:1762
#2 0x5628e96aa7f4 in format_commit_item pretty.c:1801
#3 0x5628e97cdb24 in strbuf_expand strbuf.c:429
#4 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
#5 0x5628e96acd0f in pretty_print_commit pretty.c:2161
#6 0x5628e95a44c8 in show_log log-tree.c:781
#7 0x5628e95a76ba in log_tree_commit log-tree.c:1117
#8 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
#9 0x5628e922c35b in cmd_log_walk builtin/log.c:549
#10 0x5628e922f1a2 in cmd_log builtin/log.c:883
#11 0x5628e9106993 in run_builtin git.c:466
#12 0x5628e9107397 in handle_builtin git.c:721
#13 0x5628e9107b07 in run_argv git.c:788
#14 0x5628e91088a7 in cmd_main git.c:923
#15 0x5628e939d682 in main common-main.c:57
#16 0x7f2127c3c28f (/usr/lib/libc.so.6+0x2328f)
#17 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
#18 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115
0x7f1ec62f97fe is located 2 bytes to the left of 4831838265-byte region [0x7f1ec62f9800,0x7f1fe62f9839)
allocated by thread T0 here:
#0 0x7f2127ebe7ea in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:85
#1 0x5628e98774d4 in xrealloc wrapper.c:136
#2 0x5628e97cb01c in strbuf_grow strbuf.c:99
#3 0x5628e97ccd42 in strbuf_addchars strbuf.c:327
#4 0x5628e96aa55c in format_and_pad_commit pretty.c:1761
#5 0x5628e96aa7f4 in format_commit_item pretty.c:1801
#6 0x5628e97cdb24 in strbuf_expand strbuf.c:429
#7 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
#8 0x5628e96acd0f in pretty_print_commit pretty.c:2161
#9 0x5628e95a44c8 in show_log log-tree.c:781
#10 0x5628e95a76ba in log_tree_commit log-tree.c:1117
#11 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
#12 0x5628e922c35b in cmd_log_walk builtin/log.c:549
#13 0x5628e922f1a2 in cmd_log builtin/log.c:883
#14 0x5628e9106993 in run_builtin git.c:466
#15 0x5628e9107397 in handle_builtin git.c:721
#16 0x5628e9107b07 in run_argv git.c:788
#17 0x5628e91088a7 in cmd_main git.c:923
#18 0x5628e939d682 in main common-main.c:57
#19 0x7f2127c3c28f (/usr/lib/libc.so.6+0x2328f)
#20 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
#21 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115
SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827 in __interceptor_memcpy
Shadow bytes around the buggy address:
0x0fe458c572a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0fe458c572f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa[fa]
0x0fe458c57300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==8340==ABORTING
The pretty format can also be used in `git archive` operations via the
`export-subst` attribute. So this is what in our opinion makes this a
critical issue in the context of Git forges which allow to download an
archive of user supplied Git repositories.
Fix this vulnerability by using `size_t` instead of `int` to track the
string lengths. Add tests which detect this vulnerability when Git is
compiled with the address sanitizer.
Reported-by: Joern Schneeweisz <jschneeweisz@gitlab.com>
Original-patch-by: Joern Schneeweisz <jschneeweisz@gitlab.com>
Modified-by: Taylor Blau <me@ttalorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-<commandname>.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (depending on your mood):
- random three-letter combination that is pronounceable, and not actually used by any common UNIX command. The fact that it is a mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks