On Sat, Feb 05 2022, René Scharfe wrote: > Am 31.01.22 um 22:01 schrieb Ævar Arnfjörð Bjarmason: >> >> 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? > > https://mywiki.wooledge.org/BashFAQ/068 offers a Perl-based Shell > function or aborting a program if it takes too long: > > doalarm() { perl -e 'alarm shift; exec @ARGV' -- "$@"; } > > It doesn't waste time when the program finishes faster and seems to work > fine with git grep. > > I can't actually test the effectiveness of the patch because PCRE2's > JIT doesn't work on my development machine at all (Apple M1), as I just > discovered. :-/ While we know that disabling JIT helps, we didn't > actually determine, yet, if e0c6029 (Fix inifinite loop when a single > byte newline is searched in JIT., 2020-05-29) really fixes the "^\s" > bug. > > So I have to abandon this patch, unfortunately. Any volunteer to pick > it up? We can test it in CI, and have a proposed patch from Hamza Mahfooz to do so. See https://lore.kernel.org/git/211220.865yrjszg4.gmgdl@xxxxxxxxxxxxxxxxxxx/ There's been some minor changes to the main.yml since then, but I think you should be able to just pick that patch up, adjust it, apply whatever changes you want to test on top, and push it to github.
