On Sun, Jan 30 2022, René Scharfe wrote:
> Am 30.01.22 um 10:04 schrieb SZEDER Gábor:
>> On Sun, Jan 30, 2022 at 08:55:02AM +0100, René Scharfe wrote:
>>> e0c6029 (Fix inifinite loop when a single byte newline is searched in
>>> JIT., 2020-05-29) [1] sounds like it might have fixed it. It's part of
>>> version 10.36.
>>
>> I saw this hang on two Ubuntu 20.04 based boxes, which predate that
>> fix you mention only by a month or two, and apparently the almost two
>> years since then was not enough for this fix to trickle down into
>> updated 20.04 pcre packages, because:
>>
>>> Do you still get the error when you disable JIT, i.e. when you use the
>>> pattern "(*NO_JIT)^\s" instead?
>>
>> No, with this pattern it works as expected.
>>
>> So is there a more convenient way to disable PCRE JIT in Git? FWIW,
>> (non-git) 'grep -P' works with the same patterns.
>
> I don't know a better way. We could do it automatically, though:
>
> --- >8 ---
> Subject: [PATCH] grep: disable JIT on PCRE2 before 10.36 to avoid endless loop
>
> Commit e0c6029 (Fix inifinite loop when a single byte newline is
> searched in JIT., 2020-05-29) of PCRE2 adds the following point to its
> ChangeLog for version 10.36:
>
> 2. Fix inifinite loop when a single byte newline is searched in JIT when
> invalid utf8 mode is enabled.
>
> Avoid that bug on older versions (which are still reportedly found in
> the wild) by disabling the JIT when handling UTF-8.
>
> Reported-by: SZEDER Gábor <szeder.dev@xxxxxxxxx>
> Signed-off-by: René Scharfe <l.s.r@xxxxxx>
> ---
> Not sure how to test it. Killing git grep after a second or so seems a
> bit clumsy. timeout(1) from GNU coreutils at least allows doing that
> from the shell, but it's not a standard tool. Perhaps we need a new
> test helper for that purpose?
>
> grep.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/grep.c b/grep.c
> index 7bb0360869..16629a2301 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -406,6 +406,14 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
> }
>
> pcre2_config(PCRE2_CONFIG_JIT, &p->pcre2_jit_on);
> +#ifndef GIT_PCRE2_VERSION_10_36_OR_HIGHER
> + /*
> + * Work around the bug fixed by e0c6029 (Fix inifinite loop when a
Better to quote this as PhilipHazel/pcre2@e0c6029 or something, i.e. to
indicate that it's not git.git's commit.
> + * single byte newline is searched in JIT., 2020-05-29).
> + */
> + if (options & PCRE2_MATCH_INVALID_UTF)
> + p->pcre2_jit_on = 0;
It seems rather heavy-hande, but I can't think of a better way to deal
with this, i.e. if we selectively use JIT on older versions, surely we
run into the match-bytes-but-want-chars bug you were fixing.
> +#endif
> if (p->pcre2_jit_on) {
> jitret = pcre2_jit_compile(p->pcre2_pattern, PCRE2_JIT_COMPLETE);
> if (jitret)
