[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal
From: |
Eli Zaretskii |
Subject: |
bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal |
Date: |
Sun, 25 Sep 2022 09:32:46 +0300 |
> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: 58042@debbugs.gnu.org
> Date: Sun, 25 Sep 2022 07:50:17 +0200
>
> > The GC was triggered by
> > redisplay, but how did redisplay start while regexp match was in
> > progress? Do you see any code in regexp that could trigger redisplay?
>
> I'm afraid, I don't follow. Why do you think redisplay comes into play
> here?
Because of this part of your message in
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=58042#8:
freed by thread T0 here:
#0 0x103332de4 in wrap_free+0x98
(libclang_rt.asan_osx_dynamic.dylib:arm64e+0x3ede4)
#1 0x100985e38 in rpl_free free.c:48
#2 0x1005b71a4 in lisp_free alloc.c:1038
#3 0x1005cbda4 in compact_small_strings alloc.c:2191
#4 0x1005c9f24 in sweep_strings alloc.c:2072
#5 0x1005bd028 in gc_sweep alloc.c:7397
#6 0x1005bb178 in garbage_collect alloc.c:6245
#7 0x1005ba694 in maybe_garbage_collect alloc.c:6090
#8 0x1006505ac in maybe_gc lisp.h:5624
#9 0x100648ffc in Ffuncall eval.c:2972
#10 0x10064bcd0 in internal_condition_case_n eval.c:1555
#11 0x1000cdc8c in safe__call xdisp.c:3026
#12 0x1000cdfc4 in safe__call1 xdisp.c:3062
#13 0x1001d6404 in prepare_menu_bars xdisp.c:13572
#14 0x1000f2340 in redisplay_internal xdisp.c:16523
#15 0x100108f34 in redisplay xdisp.c:16105
AFAIU, this says that the GC which freed the string data was caused by
safe__call1 inside prepare_menu_bars, which was called from
redisplay_internal.
> Anyways, my working hypotheses currently goes like this:
>
> We match using some Lisp string S and get its data pointer, say D.
> Since D is not null, S must be a live string.
>
> (Actually I didn't check that this is still the case, but I think I've
> been setting s.data to null for free strings right from the start, and I
> can't imagine why anyone would change that.)
>
> Between the point we get D, and the point of the crash, a GC happens.
> We know in principle that a GC can happen while matching since
> bug#56108. I'm taking that as a given. The GC compacts strings and
> changes S's data pointer.
>
> After GC, S.data != D.
Yes, but I have difficulty with the fact that GC was caused by
redisplay, and redisplay cannot be invoked while we are in
re_match_2_internal, AFAIK. So something else is missing here (or
maybe I'm misinterpreting the ASAN report you posted).
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Eli Zaretskii, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Eli Zaretskii, 2022/09/24
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/25
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal,
Eli Zaretskii <=
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/25
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Eli Zaretskii, 2022/09/25
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/25
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Eli Zaretskii, 2022/09/25
- bug#58042: 29.0.50; ASAN use-after-free in re_match_2_internal, Gerd Möllmann, 2022/09/26