[PING^2][PATCH][readline] Fix heap-buffer-overflow in update_line
Tom de Vries
tdevries@suse.de
Mon Jun 17 09:38:00 GMT 2019
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^2.
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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