Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[New pcre2 version] 1234qwer1234qwer4: /* References */ one-bullet lists? #21

Closed
github-actions bot opened this issue Feb 10, 2021 · 0 comments
Closed

Comments

@github-actions
Copy link

References: one-bullet lists?

← Previous revisionRevision as of 12:38, 29 December 2020Line 248:Line 248:

\* Index of /pub/pcre/: https://ftp.pcre.org/pub/pcre/

Index of /pub/pcre/: https://ftp.pcre.org/pub/pcre/

  • Exim and PCRE: How free software hijacked my life (1999-12), by [[Philip Hazel]]: https://www.ukuug.org/events/winter99/proc/PH.ps

    Exim and PCRE: How free software hijacked my life (1999-12), by [[Philip Hazel]]: https://www.ukuug.org/events/winter99/proc/PH.ps

    {{tq2|1=

    {{tq2|1=

    '''What about PCRE?'''

    '''What about PCRE?'''

    Line 256:Line 256:

    \* Written summer 1997, placed on ftp site.

    \* Written summer 1997, placed on ftp site.

    \* People found it, and started a mailing list.

    \* People found it, and started a mailing list.

    \* There has been a trickle of enhancements.|source=Exim and PCRE: How free software hijacked my life, Pg. 7}}

\* There has been a trickle of enhancements.|source=Exim and PCRE: How free software hijacked my life, Pg. 7}}

\* Regular Expression - POSIX Standard (Google Search): https://www.google.com/search?num=100&q=%22Regular+Expression%22%7C%22Regular+Expressions%22%7C%22RegEx%22%7C%22RegExp%22+site%3Apubs.opengroup.org+inurl%3Aonlinepubs%2F9699919799+-intitle%3A%22Index+of+%2Fonlinepubs%22+-inurl%3Aidx+-inurl%3Acontents.html+-inurl%3Atoc.html+-inurl%3A9699919799.orig+-inurl%3A2008edition+-inurl%3A2013edition+-inurl%3A2016edition+-inurl%3A2018edition

\* Regular Expression - POSIX Standard (Google Search): https://www.google.com/search?num=100&q=%22Regular+Expression%22%7C%22Regular+Expressions%22%7C%22RegEx%22%7C%22RegExp%22+site%3Apubs.opengroup.org+inurl%3Aonlinepubs%2F9699919799+-intitle%3A%22Index+of+%2Fonlinepubs%22+-inurl%3Aidx+-inurl%3Acontents.html+-inurl%3Atoc.html+-inurl%3A9699919799.orig+-inurl%3A2008edition+-inurl%3A2013edition+-inurl%3A2016edition+-inurl%3A2018edition

Line 263:Line 263:

\* Rationale § Regular Expressions: https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/xrat/V4\_xbd\_chap09.html#tag\_21\_09

\* Rationale § Regular Expressions: https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/xrat/V4\_xbd\_chap09.html#tag\_21\_09

\* PCRE2 - Perl-compatible regular expressions (revised API) (2020), by [[University of Cambridge]]: https://pcre.org/pcre2.txt

PCRE2 - Perl-compatible regular expressions (revised API) (2020), by [[University of Cambridge]]: https://pcre.org/pcre2.txt

\* Differences Between PCRE2 and Perl (2019-07-13), by [[Philip Hazel]]: https://www.pcre.org/current/doc/html/pcre2compat.html

Differences Between PCRE2 and Perl (2019-07-13), by [[Philip Hazel]]: https://www.pcre.org/current/doc/html/pcre2compat.html

  • Quote PCRE changelog (https://www.pcre.org/original/changelog.txt):

    Quote PCRE changelog (https://www.pcre.org/original/changelog.txt):

    {{tq2|1=

    {{tq2|1=

    Perl no longer allows group names to start with digits, so I have made this change also in PCRE.}}

Perl no longer allows group names to start with digits, so I have made this change also in PCRE.}}

\* ChangeLog for PCRE2: https://www.pcre.org/changelog.txt

ChangeLog for PCRE2: https://www.pcre.org/changelog.txt

https://en.wikipedia.org/w/index.php?title=Perl_Compatible_Regular_Expressions&diff=996974697&oldid=prev

@dscho dscho closed this as completed Feb 10, 2021
dscho pushed a commit that referenced this issue Jan 23, 2023
It is possible to trigger an integer overflow when parsing attribute
names when there are more than 2^31 of them for a single pattern. This
can either lead to us dying due to trying to request too many bytes:

     blob=$(perl -e 'print "f" . " a=" x 2147483649' | git hash-object -w --stdin)
     git update-index --add --cacheinfo 100644,$blob,.gitattributes
     git attr-check --all file

    =================================================================
    ==1022==ERROR: AddressSanitizer: requested allocation size 0xfffffff800000032 (0xfffffff800001038 after adjustments for alignment, red zones etc.) exceeds maximum supported size of 0x10000000000 (thread T0)
        #0 0x7fd3efabf411 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
        #1 0x5563a0a1e3d3 in xcalloc wrapper.c:150
        #2 0x5563a058d005 in parse_attr_line attr.c:384
        #3 0x5563a058e661 in handle_attr_line attr.c:660
        #4 0x5563a058eddb in read_attr_from_index attr.c:769
        #5 0x5563a058ef12 in read_attr attr.c:797
        #6 0x5563a058f24c in bootstrap_attr_stack attr.c:867
        #7 0x5563a058f4a3 in prepare_attr_stack attr.c:902
        #8 0x5563a05905da in collect_some_attrs attr.c:1097
        #9 0x5563a059093d in git_all_attrs attr.c:1128
        #10 0x5563a02f636e in check_attr builtin/check-attr.c:67
        #11 0x5563a02f6c12 in cmd_check_attr builtin/check-attr.c:183
        #12 0x5563a02aa993 in run_builtin git.c:466
        #13 0x5563a02ab397 in handle_builtin git.c:721
        #14 0x5563a02abb2b in run_argv git.c:788
        #15 0x5563a02ac991 in cmd_main git.c:926
        #16 0x5563a05432bd in main common-main.c:57
        #17 0x7fd3ef82228f  (/usr/lib/libc.so.6+0x2328f)

    ==1022==HINT: if you don't care about these errors you may set allocator_may_return_null=1
    SUMMARY: AddressSanitizer: allocation-size-too-big /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77 in __interceptor_calloc
    ==1022==ABORTING

Or, much worse, it can lead to an out-of-bounds write because we
underallocate and then memcpy(3P) into an array:

    perl -e '
        print "A " . "\rh="x2000000000;
        print "\rh="x2000000000;
        print "\rh="x294967294 . "\n"
    ' >.gitattributes
    git add .gitattributes
    git commit -am "evil attributes"

    $ git clone --quiet /path/to/repo
    =================================================================
    ==15062==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000002550 at pc 0x5555559884d5 bp 0x7fffffffbc60 sp 0x7fffffffbc58
    WRITE of size 8 at 0x602000002550 thread T0
        #0 0x5555559884d4 in parse_attr_line attr.c:393
        #1 0x5555559884d4 in handle_attr_line attr.c:660
        #2 0x555555988902 in read_attr_from_index attr.c:784
        #3 0x555555988902 in read_attr_from_index attr.c:747
        #4 0x555555988a1d in read_attr attr.c:800
        #5 0x555555989b0c in bootstrap_attr_stack attr.c:882
        #6 0x555555989b0c in prepare_attr_stack attr.c:917
        #7 0x555555989b0c in collect_some_attrs attr.c:1112
        #8 0x55555598b141 in git_check_attr attr.c:1126
        #9 0x555555a13004 in convert_attrs convert.c:1311
        #10 0x555555a95e04 in checkout_entry_ca entry.c:553
        #11 0x555555d58bf6 in checkout_entry entry.h:42
        #12 0x555555d58bf6 in check_updates unpack-trees.c:480
        #13 0x555555d5eb55 in unpack_trees unpack-trees.c:2040
        #14 0x555555785ab7 in checkout builtin/clone.c:724
        #15 0x555555785ab7 in cmd_clone builtin/clone.c:1384
        #16 0x55555572443c in run_builtin git.c:466
        #17 0x55555572443c in handle_builtin git.c:721
        #18 0x555555727872 in run_argv git.c:788
        #19 0x555555727872 in cmd_main git.c:926
        #20 0x555555721fa0 in main common-main.c:57
        #21 0x7ffff73f1d09 in __libc_start_main ../csu/libc-start.c:308
        #22 0x555555723f39 in _start (git+0x1cff39)

    0x602000002552 is located 0 bytes to the right of 2-byte region [0x602000002550,0x602000002552) allocated by thread T0 here:
        #0 0x7ffff768c037 in __interceptor_calloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:154
        #1 0x555555d7fff7 in xcalloc wrapper.c:150
        #2 0x55555598815f in parse_attr_line attr.c:384
        #3 0x55555598815f in handle_attr_line attr.c:660
        #4 0x555555988902 in read_attr_from_index attr.c:784
        #5 0x555555988902 in read_attr_from_index attr.c:747
        #6 0x555555988a1d in read_attr attr.c:800
        #7 0x555555989b0c in bootstrap_attr_stack attr.c:882
        #8 0x555555989b0c in prepare_attr_stack attr.c:917
        #9 0x555555989b0c in collect_some_attrs attr.c:1112
        #10 0x55555598b141 in git_check_attr attr.c:1126
        #11 0x555555a13004 in convert_attrs convert.c:1311
        #12 0x555555a95e04 in checkout_entry_ca entry.c:553
        #13 0x555555d58bf6 in checkout_entry entry.h:42
        #14 0x555555d58bf6 in check_updates unpack-trees.c:480
        #15 0x555555d5eb55 in unpack_trees unpack-trees.c:2040
        #16 0x555555785ab7 in checkout builtin/clone.c:724
        #17 0x555555785ab7 in cmd_clone builtin/clone.c:1384
        #18 0x55555572443c in run_builtin git.c:466
        #19 0x55555572443c in handle_builtin git.c:721
        #20 0x555555727872 in run_argv git.c:788
        #21 0x555555727872 in cmd_main git.c:926
        #22 0x555555721fa0 in main common-main.c:57
        #23 0x7ffff73f1d09 in __libc_start_main ../csu/libc-start.c:308

    SUMMARY: AddressSanitizer: heap-buffer-overflow attr.c:393 in parse_attr_line
    Shadow bytes around the buggy address:
      0x0c047fff8450: fa fa 00 02 fa fa 00 07 fa fa fd fd fa fa 00 00
      0x0c047fff8460: fa fa 02 fa fa fa fd fd fa fa 00 06 fa fa 05 fa
      0x0c047fff8470: fa fa fd fd fa fa 00 02 fa fa 06 fa fa fa 05 fa
      0x0c047fff8480: fa fa 07 fa fa fa fd fd fa fa 00 01 fa fa 00 02
      0x0c047fff8490: fa fa 00 03 fa fa 00 fa fa fa 00 01 fa fa 00 03
    =>0x0c047fff84a0: fa fa 00 01 fa fa 00 02 fa fa[02]fa fa fa fa fa
      0x0c047fff84b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff84c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff84d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff84e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff84f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
    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
      Shadow gap:              cc
    ==15062==ABORTING

Fix this bug by using `size_t` instead to count the number of attributes
so that this value cannot reasonably overflow without running out of
memory before already.

Reported-by: Markus Vervier <markus.vervier@x41-dsec.de>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
dscho pushed a commit that referenced this issue Jan 23, 2023
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>
dscho pushed a commit that referenced this issue Sep 13, 2024
It was recently reported that concurrent reads and writes may cause the
reftable backend to segfault. The root cause of this is that we do not
properly keep track of reftable readers across reloads.

Suppose that you have a reftable iterator and then decide to reload the
stack while iterating through the iterator. When the stack has been
rewritten since we have created the iterator, then we would end up
discarding a subset of readers that may still be in use by the iterator.
The consequence is that we now try to reference deallocated memory,
which of course segfaults.

One way to trigger this is in t5616, where some background maintenance
jobs have been leaking from one test into another. This leads to stack
traces like the following one:

  + git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 --refetch origin
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==657994==ERROR: AddressSanitizer: SEGV on unknown address 0x7fa0f0ec6089 (pc 0x55f23e52ddf9 bp
0x7ffe7bfa1700 sp 0x7ffe7bfa1700 T0)
  ==657994==The signal is caused by a READ memory access.
      #0 0x55f23e52ddf9 in get_var_int reftable/record.c:29
      #1 0x55f23e53295e in reftable_decode_keylen reftable/record.c:170
      #2 0x55f23e532cc0 in reftable_decode_key reftable/record.c:194
      #3 0x55f23e54e72e in block_iter_next reftable/block.c:398
      #4 0x55f23e5573dc in table_iter_next_in_block reftable/reader.c:240
      #5 0x55f23e5573dc in table_iter_next reftable/reader.c:355
      #6 0x55f23e5573dc in table_iter_next reftable/reader.c:339
      #7 0x55f23e551283 in merged_iter_advance_subiter reftable/merged.c:69
      #8 0x55f23e55169e in merged_iter_next_entry reftable/merged.c:123
      #9 0x55f23e55169e in merged_iter_next_void reftable/merged.c:172
      #10 0x55f23e537625 in reftable_iterator_next_ref reftable/generic.c:175
      #11 0x55f23e2cf9c6 in reftable_ref_iterator_advance refs/reftable-backend.c:464
      #12 0x55f23e2d996e in ref_iterator_advance refs/iterator.c:13
      #13 0x55f23e2d996e in do_for_each_ref_iterator refs/iterator.c:452
      #14 0x55f23dca6767 in get_ref_map builtin/fetch.c:623
      #15 0x55f23dca6767 in do_fetch builtin/fetch.c:1659
      #16 0x55f23dca6767 in fetch_one builtin/fetch.c:2133
      #17 0x55f23dca6767 in cmd_fetch builtin/fetch.c:2432
      #18 0x55f23dba7764 in run_builtin git.c:484
      #19 0x55f23dba7764 in handle_builtin git.c:741
      #20 0x55f23dbab61e in run_argv git.c:805
      #21 0x55f23dbab61e in cmd_main git.c:1000
      #22 0x55f23dba4781 in main common-main.c:64
      #23 0x7fa0f063fc89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      #24 0x7fa0f063fd44 in __libc_start_main_impl ../csu/libc-start.c:360
      #25 0x55f23dba6ad0 in _start (git+0xadfad0) (BuildId: 803b2b7f59beb03d7849fb8294a8e2145dd4aa27)

While it is somewhat awkward that the maintenance processes survive
tests in the first place, it is totally expected that reftables should
work alright with concurrent writers. Seemingly they don't.

The only underlying resource that we need to care about in this context
is the reftable reader, which is responsible for reading a single table
from disk. These readers get discarded immediately (unless reused) when
calling `reftable_stack_reload()`, which is wrong. We can only close
them once we know that there are no iterators using them anymore.

Prepare for a fix by converting the reftable readers to be refcounted.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
Development

No branches or pull requests

1 participant