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[PING^3][PATCH][readline] Fix heap-buffer-overflow in update_line


On 17-06-19 11:38, Tom de Vries wrote:
> On 10-06-19 20:36, Tom de Vries wrote:
>> On 25-05-19 13:24, Tom de Vries wrote:
>>> Hi,
>>>
>>> When:
>>> - building trunk gdb with '-fsanitize=address -lasan',
>>> - running gdb tests with "export ASAN_OPTIONS=detect_leaks=0",
>>> I run into a heap-buffer-overflow failure for
>>> gdb.base/utf8-identifiers.exp.
>>>
>>> In more detail, the libasan error report looks like this:
>>> ...
>>> =================================================================
>>> ==22340==ERROR: AddressSanitizer: heap-buffer-overflow on address
>>> 0x619000054a80 at pc 0x7fcd0306b4c9 bp 0x7fffb1a8d880 sp 0x7fffb1a8d030
>>> READ of size 32766 at 0x619000054a80 thread T0
>>>     #0 0x7fcd0306b4c8  (/usr/lib64/libasan.so.4+0xae4c8)
>>>     #1 0x15f12a1 in update_line
>>> /data/gdb_versions/devel/src/readline/display.c:1377
>>>     #2 0x15f03cb in rl_redisplay
>>> /data/gdb_versions/devel/src/readline/display.c:1204
>>>     #3 0x15bf932 in readline_internal_setup
>>> /data/gdb_versions/devel/src/readline/readline.c:394
>>>     #4 0x15fe723 in _rl_callback_newline
>>> /data/gdb_versions/devel/src/readline/callback.c:89
>>>     #5 0x15fe7ef in rl_callback_handler_install
>>> /data/gdb_versions/devel/src/readline/callback.c:102
>>>     #6 0xd7bce6 in gdb_rl_callback_handler_install(char const*)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:319
>>>     #7 0xd7c0c6 in display_gdb_prompt(char const*)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:409
>>>     #8 0xd7d6c1 in command_line_handler(std::unique_ptr<char,
>>> gdb::xfree_deleter<char> >&&)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:776
>>>     #9 0xd7b92a in gdb_rl_callback_handler
>>> /data/gdb_versions/devel/src/gdb/event-top.c:217
>>>     #10 0x15ff479 in rl_callback_read_char
>>> /data/gdb_versions/devel/src/readline/callback.c:220
>>>     #11 0xd7b4d5 in gdb_rl_callback_read_char_wrapper_noexcept
>>> /data/gdb_versions/devel/src/gdb/event-top.c:175
>>>     #12 0xd7b6b5 in gdb_rl_callback_read_char_wrapper
>>> /data/gdb_versions/devel/src/gdb/event-top.c:192
>>>     #13 0xd7c8aa in stdin_event_handler(int, void*)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:514
>>>     #14 0xd76ca7 in handle_file_event
>>> /data/gdb_versions/devel/src/gdb/event-loop.c:731
>>>     #15 0xd7751f in gdb_wait_for_event
>>> /data/gdb_versions/devel/src/gdb/event-loop.c:857
>>>     #16 0xd7547e in gdb_do_one_event()
>>> /data/gdb_versions/devel/src/gdb/event-loop.c:321
>>>     #17 0xd75526 in start_event_loop()
>>> /data/gdb_versions/devel/src/gdb/event-loop.c:370
>>>     #18 0x101b04c in captured_command_loop
>>> /data/gdb_versions/devel/src/gdb/main.c:331
>>>     #19 0x101de73 in captured_main
>>> /data/gdb_versions/devel/src/gdb/main.c:1173
>>>     #20 0x101df03 in gdb_main(captured_main_args*)
>>> /data/gdb_versions/devel/src/gdb/main.c:1188
>>>     #21 0x872dba in main /data/gdb_versions/devel/src/gdb/gdb.c:32
>>>     #22 0x7fcd00f2ff49 in __libc_start_main (/lib64/libc.so.6+0x20f49)
>>>     #23 0x872bc9 in _start (/data/gdb_versions/devel/build/gdb/gdb+0x872bc9)
>>>
>>> 0x619000054a80 is located 0 bytes to the right of 1024-byte region
>>> [0x619000054680,0x619000054a80)
>>> allocated by thread T0 here:
>>>     #0 0x7fcd03099510 in malloc (/usr/lib64/libasan.so.4+0xdc510)
>>>     #1 0xae0078 in xmalloc
>>> /data/gdb_versions/devel/src/gdb/common/common-utils.c:44
>>>     #2 0x15eaccb in init_line_structures
>>> /data/gdb_versions/devel/src/readline/display.c:458
>>>     #3 0x15eb4d8 in rl_redisplay
>>> /data/gdb_versions/devel/src/readline/display.c:526
>>>     #4 0x15bf932 in readline_internal_setup
>>> /data/gdb_versions/devel/src/readline/readline.c:394
>>>     #5 0x15fe723 in _rl_callback_newline
>>> /data/gdb_versions/devel/src/readline/callback.c:89
>>>     #6 0x15fe7ef in rl_callback_handler_install
>>> /data/gdb_versions/devel/src/readline/callback.c:102
>>>     #7 0xd7bce6 in gdb_rl_callback_handler_install(char const*)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:319
>>>     #8 0xd7c0c6 in display_gdb_prompt(char const*)
>>> /data/gdb_versions/devel/src/gdb/event-top.c:409
>>>     #9 0xaa041b in cli_interp_base::pre_command_loop()
>>> /data/gdb_versions/devel/src/gdb/cli/cli-interp.c:286
>>>     #10 0xf5342a in interp_pre_command_loop(interp*)
>>> /data/gdb_versions/devel/src/gdb/interps.c:320
>>>     #11 0x101b047 in captured_command_loop
>>> /data/gdb_versions/devel/src/gdb/main.c:328
>>>     #12 0x101de73 in captured_main
>>> /data/gdb_versions/devel/src/gdb/main.c:1173
>>>     #13 0x101df03 in gdb_main(captured_main_args*)
>>> /data/gdb_versions/devel/src/gdb/main.c:1188
>>>     #14 0x872dba in main /data/gdb_versions/devel/src/gdb/gdb.c:32
>>>     #15 0x7fcd00f2ff49 in __libc_start_main (/lib64/libc.so.6+0x20f49)
>>>
>>> SUMMARY: AddressSanitizer: heap-buffer-overflow
>>> (/usr/lib64/libasan.so.4+0xae4c8)
>>> Shadow bytes around the buggy address:
>>>   0x0c3280002900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002910: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002920: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002930: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002940: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> =>0x0c3280002950:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>>>   0x0c3280002960: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
>>>   0x0c3280002970: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c3280002990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>>   0x0c32800029a0: 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
>>> ==22340==ABORTING
>>> ...
>>>
>>> I've written an assert in rl_redisplay that formulates the error condition:
>>> ...
>>> @@ -1387,6 +1389,10 @@ rl_redisplay (void)
>>>           cpos_adjusted = 0;
>>> +         assert (last_lmargin + (_rl_screenwidth + visible_wrap_offset)
>>> +                 <= line_size);
>>> +         assert (lmargin + (_rl_screenwidth + (lmargin ? 0 : wrap_offset))
>>> +                 <= line_size);
>>>           update_line (&visible_line[last_lmargin],
>>>                        &invisible_line[lmargin],
>>>                        0,
>>>                        _rl_screenwidth + visible_wrap_offset,
>>>                        _rl_screenwidth + (lmargin ? 0 : wrap_offset),
>>>                        0);
>>> ...
>>> which triggers without needing the address sanitizer (or even an executable),
>>> like this:
>>> ...
>>> $ TERM=dumb gdb -q -ex "set width 0"
>>> gdb: src/display.c:1393: rl_redisplay: Assertion
>>> `last_lmargin + (_rl_screenwidth + visible_wrap_offset) <= line_size'
>>> failed.
>>> Aborted (core dumped)
>>> ...
>>>
>>> The basic problem is this: visible_line and invisible_line have length
>>> line_size, but the update_line call assumes that line_size is at least
>>> _rl_screenwidth + 1.  Executing "set width 0" sets _rl_screenwidth to 32766 but
>>> doesn't affect line_size, which is initialized to 1024.
>>>
>>> Fix this by ensuring in init_line_structures and rl_redisplay that line_size
>>> is at least _rl_screenwidth + 1.
>>>
>>> Tested on x86_64-linux.
>>>
>>> Reviewed by readline maintainer (
>>> https://sourceware.org/ml/gdb-patches/2019-05/msg00566.html ).
>>>
>>> OK for binutils-gdb repo copy of readline?
>>>
>>
> 

Ping^3.

Thanks,
- Tom

>>> [readline] Fix heap-buffer-overflow in update_line
>>>
>>> readline/ChangeLog.gdb:
>>>
>>> 2019-05-25  Tom de Vries  <tdevries@suse.de>
>>> 	    Chet Ramey  <chet.ramey@case.edu>
>>>
>>> 	PR cli/24514
>>> 	* readline/display.c (init_line_structures, rl_redisplay): Ensure
>>> 	line_size is at	least _rl_screenwidth + 1.
>>>
>>> ---
>>>  readline/display.c | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/readline/display.c b/readline/display.c
>>> index 9044305797..842adf5067 100644
>>> --- a/readline/display.c
>>> +++ b/readline/display.c
>>> @@ -450,6 +450,9 @@ init_line_structures (minsize)
>>>  {
>>>    register int n;
>>>  
>>> +  if (minsize <= _rl_screenwidth)	/* XXX - for gdb */
>>> +    minsize = _rl_screenwidth + 1;
>>> +
>>>    if (invisible_line == 0)	/* initialize it */
>>>      {
>>>        if (line_size < minsize)
>>> @@ -526,6 +529,8 @@ rl_redisplay ()
>>>        init_line_structures (0);
>>>        rl_on_new_line ();
>>>      }
>>> +  else if (line_size <= _rl_screenwidth)
>>> +    init_line_structures (_rl_screenwidth + 1);
>>>  
>>>    /* Draw the line into the buffer. */
>>>    cpos_buffer_position = -1;
>>>


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