[Bug gdb/28114] New: heap-buffer-overflow with gdb dir command

[Bug gdb/28114] New: heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

            Bug ID: 28114
           Summary: heap-buffer-overflow with gdb dir command
           Product: gdb
           Version: 10.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: again.liu at gmail dot com
  Target Milestone: ---

Hi, I am here to report a bug I found with AFL++, with afl-clang-fast++2.68c.
I choose the version as 10.1, but this bug also exist in 10.2.

The OS information of the Ubuntu build I used:
--
root@ubuntu:~/Desktop$ cat /etc/os-*
NAME="Ubuntu"
VERSION="20.04.2 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.2 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
--

The source was downloaded from the following URLs.
http://ftp.gnu.org/gnu/gdb/gdb-10.1.tar.gz
http://ftp.gnu.org/gnu/gdb/gdb-10.2.tar.gz

Configuration option was:
CC=afl-clang-fast CXX=afl-clang-fast++ AFL_USE_ASAN=1 ./configure
CC=afl-clang-fast CXX=afl-clang-fast++ AFL_USE_ASAN=1 make -j$(nproc)

To reproduce with 10.2:
root@ubuntu:/tmp/gdb-10.2$ echo "dir:" > /tmp/test && ./gdb/gdb -x /tmp/test

The following are the addressSanitizer report with 10.2 running.
--
==17806==ERROR: AddressSanitizer: heap-buffer-overflow on address
0x6020000134cf at pc 0x000000e2901c bp 0x7fffffffced0 sp 0x7fffffffcec8
READ of size 1 at 0x6020000134cf thread T0
    #0 0xe2901b in add_path(char const*, char**, int)
/tmp/gdb-10.2/gdb/source.c:530:10
    #1 0xe2ea3f in mod_path(char const*, char**)
/tmp/gdb-10.2/gdb/source.c:482:3
    #2 0xe2ea3f in directory_command(char const*, int)
/tmp/gdb-10.2/gdb/source.c:461:7
    #3 0x6dfacf in cmd_func(cmd_list_element*, char const*, int)
/tmp/gdb-10.2/gdb/cli/cli-decode.c:2181:7
    #4 0xf9b992 in execute_command(char const*, int)
/tmp/gdb-10.2/gdb/top.c:668:2
    #5 0x979e72 in command_handler(char const*)
/tmp/gdb-10.2/gdb/event-top.c:588:7
    #6 0xf98e9e in read_command_file(_IO_FILE*) /tmp/gdb-10.2/gdb/top.c:447:7
    #7 0x6fde36 in script_from_file(_IO_FILE*, char const*)
/tmp/gdb-10.2/gdb/cli/cli-script.c:1622:7
    #8 0x6c6870 in source_script_from_stream(_IO_FILE*, char const*, char
const*) /tmp/gdb-10.2/gdb/cli/cli-cmds.c:700:3
    #9 0x6c6870 in source_script_with_search(char const*, int, int)
/tmp/gdb-10.2/gdb/cli/cli-cmds.c:736:3
    #10 0xbc185e in catch_command_errors(void (*)(char const*, int), char
const*, int) /tmp/gdb-10.2/gdb/main.c:457:7
    #11 0xbc185e in captured_main_1(captured_main_args*)
/tmp/gdb-10.2/gdb/main.c:1214:10
    #12 0xbbe0f8 in captured_main(void*) /tmp/gdb-10.2/gdb/main.c:1243:3
    #13 0xbbe0f8 in gdb_main(captured_main_args*)
/tmp/gdb-10.2/gdb/main.c:1268:7
    #14 0x4e26e5 in main /tmp/gdb-10.2/gdb/gdb.c:32:10
    #15 0x7ffff78cb0b2 in __libc_start_main
/build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:308:16
    #16 0x435f8d in _start (/tmp/gdb-10.2/gdb/gdb+0x435f8d)

0x6020000134cf is located 1 bytes to the left of 1-byte region
[0x6020000134d0,0x6020000134d1)
allocated by thread T0 here:
    #0 0x4afffd in malloc (/tmp/gdb-10.2/gdb/gdb+0x4afffd)
    #1 0x575436 in xmalloc /tmp/gdb-10.2/gdb/alloc.c:60:9
    #2 0xe2828b in add_path(char const*, char**, int)
/tmp/gdb-10.2/gdb/source.c:508:2
    #3 0xe2ea3f in mod_path(char const*, char**)
/tmp/gdb-10.2/gdb/source.c:482:3
    #4 0xe2ea3f in directory_command(char const*, int)
/tmp/gdb-10.2/gdb/source.c:461:7
    #5 0x6dfacf in cmd_func(cmd_list_element*, char const*, int)
/tmp/gdb-10.2/gdb/cli/cli-decode.c:2181:7
    #6 0xf9b992 in execute_command(char const*, int)
/tmp/gdb-10.2/gdb/top.c:668:2
    #7 0x979e72 in command_handler(char const*)
/tmp/gdb-10.2/gdb/event-top.c:588:7
    #8 0xf98e9e in read_command_file(_IO_FILE*) /tmp/gdb-10.2/gdb/top.c:447:7
    #9 0x6c6870 in source_script_from_stream(_IO_FILE*, char const*, char
const*) /tmp/gdb-10.2/gdb/cli/cli-cmds.c:700:3
    #10 0x6c6870 in source_script_with_search(char const*, int, int)
/tmp/gdb-10.2/gdb/cli/cli-cmds.c:736:3
    #11 0xbc185e in catch_command_errors(void (*)(char const*, int), char
const*, int) /tmp/gdb-10.2/gdb/main.c:457:7
    #12 0xbc185e in captured_main_1(captured_main_args*)
/tmp/gdb-10.2/gdb/main.c:1214:10
    #13 0xbbe0f8 in captured_main(void*) /tmp/gdb-10.2/gdb/main.c:1243:3
    #14 0xbbe0f8 in gdb_main(captured_main_args*)
/tmp/gdb-10.2/gdb/main.c:1268:7
    #15 0x7ffff78cb0b2 in __libc_start_main
/build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:308:16

SUMMARY: AddressSanitizer: heap-buffer-overflow
/tmp/gdb-10.2/gdb/source.c:530:10 in add_path(char const*, char**, int)
Shadow bytes around the buggy address:
  0x0c047fffa640: fa fa fd fa fa fa fd fa fa fa fd fd fa fa fd fa
  0x0c047fffa650: fa fa fd fa fa fa fd fa fa fa fd fd fa fa fd fa
  0x0c047fffa660: fa fa fd fa fa fa fd fa fa fa fd fd fa fa fd fd
  0x0c047fffa670: fa fa fd fa fa fa fd fa fa fa fd fa fa fa fd fa
  0x0c047fffa680: fa fa fd fa fa fa fd fa fa fa fd fa fa fa 00 fa
=>0x0c047fffa690: fa fa fd fa fa fa fd fa fa[fa]01 fa fa fa fd fa
  0x0c047fffa6a0: fa fa 01 fa fa fa 00 00 fa fa fa fa fa fa fa fa
  0x0c047fffa6b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fffa6c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fffa6d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fffa6e0: 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
==17806==ABORTING
--

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

again.liu at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |again.liu at gmail dot com

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

--- Comment #1 from again.liu at gmail dot com ---
Also confirmed that the same crash happens in the HEAD of gdb-10-branch.

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

Hannes Domani <ssbssa at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ssbssa at sourceware dot org

--- Comment #2 from Hannes Domani <ssbssa at sourceware dot org> ---
I think this was fixed on master with this commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=baea2f9d52d606f6b58a736420017c98351f5b5c

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

--- Comment #3 from kurisu <again.liu at gmail dot com> ---
Confirmed that this crash won't happen after the following commit:
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=bb3a4efe13c0bd9a7b15ecd02ddb966870a03bd0

However somehow the fix did not go into the 10.2 releases.

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

--- Comment #4 from kurisu <again.liu at gmail dot com> ---
the bb3a4efe13c0bd9a7b15ecd02ddb966870a03bd0 commit exist in the gdb-11-branch
but not in the gdb-10-branch.

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |simark at simark dot ca

--- Comment #5 from Simon Marchi <simark at simark dot ca> ---
This is expect, as there won't be any more GDB 10 releases, so we don't
backport fixes there.

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[again.liu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

--- Comment #6 from kurisu <again.liu at gmail dot com> ---
Understood. I will register a cve for this just for the record.
Thanks for confirming.

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[Bug gdb/28114] heap-buffer-overflow with gdb dir command

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28114

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |tromey at sourceware dot org
   Target Milestone|---                         |11.1
         Resolution|---                         |FIXED

--- Comment #7 from Tom Tromey <tromey at sourceware dot org> ---
Fixed in 11.

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