grep: work around UTF-8 related JIT bug in PCRE2 <= 10.34

Stephane is reporting[1] a regression introduced in git v2.40.0 that leads
to 'git grep' segfaulting in his CI pipeline. It turns out, he's using an
older version of libpcre2 that triggers a wild pointer dereference in
the generated JIT code that was fixed in PCRE2 10.35.

Instead of completely disabling the JIT compiler for the buggy version,
just mask out the Unicode property handling as we used to do prior to
commit acabd20 ("grep: correctly identify utf-8 characters with
\{b,w} in -P").

[1] https://lore.kernel.org/git/[email protected]/

Reported-by: Stephane Odul <[email protected]>
Signed-off-by: Mathias Krause <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: minipli-oss

grep.c

@@ -295,6 +295,15 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	if (!opt->ignore_locale && is_utf8_locale() && !literal)
 		options |= (PCRE2_UTF | PCRE2_UCP | PCRE2_MATCH_INVALID_UTF);
 
+#ifndef GIT_PCRE2_VERSION_10_35_OR_HIGHER
+	/*
+	 * Work around a JIT bug related to invalid Unicode character handling
+	 * fixed in 10.35:
+	 * https://github.com/PCRE2Project/pcre2/commit/c21bd977547d
+	 */
+	options &= ~PCRE2_UCP;
+#endif
+
 #ifndef GIT_PCRE2_VERSION_10_36_OR_HIGHER
 	/* Work around https://bugs.exim.org/show_bug.cgi?id=2642 fixed in 10.36 */
 	if (PCRE2_MATCH_INVALID_UTF && options & (PCRE2_UTF | PCRE2_CASELESS))

grep.h

@@ -7,6 +7,9 @@
 #if (PCRE2_MAJOR >= 10 && PCRE2_MINOR >= 36) || PCRE2_MAJOR >= 11
 #define GIT_PCRE2_VERSION_10_36_OR_HIGHER
 #endif
+#if (PCRE2_MAJOR >= 10 && PCRE2_MINOR >= 35) || PCRE2_MAJOR >= 11
+#define GIT_PCRE2_VERSION_10_35_OR_HIGHER
+#endif
 #if (PCRE2_MAJOR >= 10 && PCRE2_MINOR >= 34) || PCRE2_MAJOR >= 11
 #define GIT_PCRE2_VERSION_10_34_OR_HIGHER
 #endif