From: Johannes Schindelin <johannes.schindelin@gmx.de>
To: git@vger.kernel.org
Cc: "Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
"Benjamin Kramer" <benny.kra@googlemail.com>,
"René Scharfe" <l.s.r@web.de>
Subject: [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data
Date: Wed, 21 Sep 2016 20:23:11 +0200 (CEST) [thread overview]
Message-ID: <cover.1474482164.git.johannes.schindelin@gmx.de> (raw)
In-Reply-To: <cover.1473321437.git.johannes.schindelin@gmx.de>
[-- Attachment #1: Type: text/plain, Size: 4565 bytes --]
[Cc:ing Benjamin Kramer & René Scharfe because they both worked on
the REG_STARTEND code in grep.c that I replace in this iteration of the
patch series]
This patch series addresses a problem where `git diff` is called using
`-G` or `-S --pickaxe-regex` on new-born files that are configured
without user diff drivers, and that hence get mmap()ed into memory.
The problem with that: mmap()ed memory is *not* NUL-terminated, yet the
pickaxe code calls regexec() on it just the same.
This problem has been reported by my colleague Chris Sidi.
We solve this by introducing a helper, regexec_buf(), that takes a
pointer and a length instead of a NUL-terminated string.
This helper then uses REG_STARTEND where available, and falls back to
allocating and constructing a NUL-terminated string. Given the
wide-spread support for REG_STARTEND (Linux has it, MacOSX has it, Git
for Windows has it because it uses compat/regex/ that has it), I think
this is a fair trade-off.
Changes since v3:
- reworded the onelines as per Junio's suggestions.
- removed fallback when REG_STARTEND is not supported, in favor of
requiring NO_REGEX.
- removed the regmatch() function from grep.c, in favor of using
regexec_buf().
Johannes Schindelin (3):
regex: -G<pattern> feeds a non NUL-terminated string to regexec() and
fails
regex: add regexec_buf() that can work on a non NUL-terminated string
regex: use regexec_buf()
Makefile | 3 ++-
diff.c | 3 ++-
diffcore-pickaxe.c | 18 ++++++++----------
git-compat-util.h | 13 +++++++++++++
grep.c | 14 ++------------
t/t4061-diff-pickaxe.sh | 22 ++++++++++++++++++++++
xdiff-interface.c | 13 ++++---------
7 files changed, 53 insertions(+), 33 deletions(-)
create mode 100755 t/t4061-diff-pickaxe.sh
Published-As: https://github.com/dscho/git/releases/tag/mmap-regexec-v4
Fetch-It-Via: git fetch https://github.com/dscho/git mmap-regexec-v4
Interdiff vs v3:
diff --git a/Makefile b/Makefile
index df4f86b..c6f7f66 100644
--- a/Makefile
+++ b/Makefile
@@ -301,7 +301,8 @@ all::
# crashes due to allocation and free working on different 'heaps'.
# It's defined automatically if USE_NED_ALLOCATOR is set.
#
-# Define NO_REGEX if you have no or inferior regex support in your C library.
+# Define NO_REGEX if your C library lacks regex support with REG_STARTEND
+# feature.
#
# Define HAVE_DEV_TTY if your system can open /dev/tty to interact with the
# user.
diff --git a/git-compat-util.h b/git-compat-util.h
index 627ec5f..8aab0c3 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -977,25 +977,17 @@ void git_qsort(void *base, size_t nmemb, size_t size,
#define qsort git_qsort
#endif
+#ifndef REG_STARTEND
+#error "Git requires REG_STARTEND support. Compile with NO_REGEX=NeedsStartEnd"
+#endif
+
static inline int regexec_buf(const regex_t *preg, const char *buf, size_t size,
size_t nmatch, regmatch_t pmatch[], int eflags)
{
-#ifdef REG_STARTEND
assert(nmatch > 0 && pmatch);
pmatch[0].rm_so = 0;
pmatch[0].rm_eo = size;
return regexec(preg, buf, nmatch, pmatch, eflags | REG_STARTEND);
-#else
- char *buf2 = xmalloc(size + 1);
- int ret;
-
- memcpy(buf2, buf, size);
- buf2[size] = '\0';
- ret = regexec(preg, buf2, nmatch, pmatch, eflags);
- free(buf2);
-
- return ret;
-#endif
}
#ifndef DIR_HAS_BSD_GROUP_SEMANTICS
diff --git a/grep.c b/grep.c
index d7d00b8..1194d35 100644
--- a/grep.c
+++ b/grep.c
@@ -898,17 +898,6 @@ static int fixmatch(struct grep_pat *p, char *line, char *eol,
}
}
-static int regmatch(const regex_t *preg, char *line, char *eol,
- regmatch_t *match, int eflags)
-{
-#ifdef REG_STARTEND
- match->rm_so = 0;
- match->rm_eo = eol - line;
- eflags |= REG_STARTEND;
-#endif
- return regexec(preg, line, 1, match, eflags);
-}
-
static int patmatch(struct grep_pat *p, char *line, char *eol,
regmatch_t *match, int eflags)
{
@@ -919,7 +908,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol,
else if (p->pcre_regexp)
hit = !pcrematch(p, line, eol, match, eflags);
else
- hit = !regmatch(&p->regexp, line, eol, match, eflags);
+ hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
+ eflags);
return hit;
}
--
2.10.0.windows.1.10.g803177d
base-commit: f6727b0509ec3417a5183ba6e658143275a734f5
next prev parent reply other threads:[~2016-09-21 18:23 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-05 15:44 [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-05 15:45 ` [PATCH 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-06 18:43 ` Jeff King
2016-09-08 7:53 ` Johannes Schindelin
2016-09-05 15:45 ` [PATCH 2/3] diff_populate_filespec: NUL-terminate buffers Johannes Schindelin
2016-09-06 7:06 ` Jeff King
2016-09-06 16:02 ` Johannes Schindelin
2016-09-06 18:41 ` Jeff King
2016-09-07 18:31 ` Junio C Hamano
2016-09-08 7:52 ` Johannes Schindelin
2016-09-08 7:49 ` Johannes Schindelin
2016-09-08 8:22 ` Jeff King
2016-09-08 16:57 ` Junio C Hamano
2016-09-08 18:22 ` Johannes Schindelin
2016-09-08 18:48 ` Jeff King
2016-09-05 15:45 ` [PATCH 3/3] diff_grep: add assertions verifying that the buffers are NUL-terminated Johannes Schindelin
2016-09-06 7:08 ` Jeff King
2016-09-06 16:04 ` Johannes Schindelin
2016-09-05 19:10 ` [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Junio C Hamano
2016-09-06 7:12 ` Jeff King
2016-09-06 14:06 ` Johannes Schindelin
2016-09-06 18:29 ` Jeff King
2016-09-08 7:29 ` Johannes Schindelin
2016-09-08 8:00 ` Jeff King
2016-09-09 10:09 ` Johannes Schindelin
2016-09-09 17:46 ` Junio C Hamano
2016-09-06 13:21 ` Johannes Schindelin
2016-09-06 6:58 ` Jeff King
2016-09-06 14:13 ` Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 " Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 8:04 ` Jeff King
2016-09-09 9:45 ` Johannes Schindelin
2016-09-09 9:59 ` Jeff King
2016-09-08 7:31 ` [PATCH v2 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 7:54 ` Johannes Schindelin
2016-09-08 8:10 ` Jeff King
2016-09-08 8:14 ` Jeff King
2016-09-08 8:35 ` Jeff King
2016-09-08 19:06 ` Ramsay Jones
2016-09-08 19:53 ` Jeff King
2016-09-08 21:30 ` Junio C Hamano
2016-09-08 7:33 ` [PATCH v2 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-08 8:13 ` Jeff King
2016-09-08 7:57 ` [PATCH v3 " Johannes Schindelin
2016-09-08 7:57 ` [PATCH v3 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:58 ` [PATCH v3 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 17:03 ` Junio C Hamano
2016-09-08 7:59 ` [PATCH v3 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 17:09 ` Junio C Hamano
2016-09-09 9:52 ` Johannes Schindelin
2016-09-09 9:57 ` Jeff King
2016-09-09 10:41 ` Johannes Schindelin
2016-09-09 17:49 ` Junio C Hamano
2016-09-21 18:23 ` Johannes Schindelin [this message]
2016-09-21 18:23 ` [PATCH v4 1/3] regex: -G<pattern> feeds a non NUL-terminated string to regexec() and fails Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 2/3] regex: add regexec_buf() that can work on a non NUL-terminated string Johannes Schindelin
2016-09-21 19:17 ` Junio C Hamano
2016-09-22 18:38 ` Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 3/3] regex: use regexec_buf() Johannes Schindelin
2016-09-21 19:18 ` Junio C Hamano
2016-09-21 20:09 ` Junio C Hamano
2016-09-21 22:03 ` Jeff King
2016-09-25 14:01 ` Johannes Schindelin
2016-09-21 22:04 ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Jeff King
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