@matheusbsbs / matheus-bagliano / commits / 17154b1576

regex: do not call `regfree()` if compilation fails

It is apparently undefined behavior to call `regfree()` on a regex where `regcomp()` failed. The language in [1] is a bit muddy, at least to me, but the clearest hint is this (`preg` is the `regex_t *`): Upon successful completion, the regcomp() function shall return 0. Otherwise, it shall return an integer value indicating an error as described in <regex.h>, and the content of preg is undefined. Funnily enough, there is also the `regerror()` function which should be given a pointer to such a "failed" `regex_t` -- the content of which would supposedly be undefined -- and which may investigate it to come up with a detailed error message. In any case, the example in that document shows how `regfree()` is not called after `regcomp()` fails. We have quite a few users of this API and most get this right. These three users do not. Several implementations can handle this just fine [2] and these code paths supposedly have not wreaked havoc or we'd have heard about it. (These are all in code paths where git got bad input and is just about to die anyway.) But let's just avoid the issue altogether. [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/regcomp.html [2] https://www.redhat.com/archives/libvir-list/2013-September/msg00262.html Researched-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-byi Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Martin Ågren committed May 20, 2018 at 12:50 UTC 17154b1576f8be5aa3044f3adadb5473da618a42

2 files changed -3

diffcore-pickaxe.c

-1

@@ -215,7 +215,6 @@ static void regcomp_or_die(regex_t *regex, const char *needle, int cflags)

215 /* The POSIX.2 people are surely sick */

216 char errbuf[1024];

217 regerror(err, regex, errbuf, 1024);

218 - regfree(regex);

218 die("invalid regex: %s", errbuf);

219 }

220 }

grep.c

-2

@@ -636,7 +636,6 @@ static void compile_fixed_regexp(struct grep_pat *p, struct grep_opt *opt)

636 if (err) {

637 char errbuf[1024];

638 regerror(err, &p->regexp, errbuf, sizeof(errbuf));

639 - regfree(&p->regexp);

639 compile_regexp_failed(p, errbuf);

640 }

641 }

@@ -701,7 +700,6 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)

700 if (err) {

701 char errbuf[1024];

702 regerror(err, &p->regexp, errbuf, 1024);

704 - regfree(&p->regexp);

703 compile_regexp_failed(p, errbuf);

704 }

705 }