Re: [RFC PATCH v5 0/3] grep: almost no more leaks, hopefully no crashes

["René Scharfe" <l.s.r@web.de>]

Am 09.08.19 um 13:24 schrieb Carlo Arenas:
> disregard this version, it still broken (and wouldn't even build on
> some cases), the reasons why are still unclear though but at least it
> might
> seem from the last known run in windows that segfaults were prevented
> at last and something was still off enough to trigger a BUG (shouldn't
> be a concern with V6 or later that do PCRE2 migration to NED fully, as
> agreed)

So how about starting stupidly simple?  You can test it everywhere, it
just needs libpcre2.  It works without that library as well (tested with
"make USE_LIBPCRE= USE_LIBPCRE2= test"), but doesn't allocate anything
in that case, of course.  The character tables leak fix should be safe
on top.  If you detect performance issues then we can address them in
additional patches.

-- >8 --
Subject: [PATCH] grep: use xmalloc() for all PCRE2 allocations

Build a PCRE2 global custom context when compiling a pattern and use it
to tell the library to use xmalloc() for allocations.  This provides
consistent out-of-memory handling and makes sure it uses a custom
allocator, e.g. with USE_NED_ALLOCATOR.

Signed-off-by: René Scharfe <l.s.r@web.de>
---
The function names are ridiculously long, I tried to stay within 80
characters per line but gave up in the end and just kept going without
line breaks.  Fits the "stupidly simple" approach..

 grep.c | 23 +++++++++++++++++------
 grep.h |  2 ++
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/grep.c b/grep.c
index cd952ef5d3..44f4e38657 100644
--- a/grep.c
+++ b/grep.c
@@ -482,6 +482,16 @@ static void free_pcre1_regexp(struct grep_pat *p)
 #endif /* !USE_LIBPCRE1 */

 #ifdef USE_LIBPCRE2
+static void *pcre2_malloc(PCRE2_SIZE size, MAYBE_UNUSED void *memory_data)
+{
+	return xmalloc(size);
+}
+
+static void pcre2_free(void *pointer, MAYBE_UNUSED void *memory_data)
+{
+	free(pointer);
+}
+
 static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
 {
 	int error;
@@ -495,12 +505,12 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt

 	assert(opt->pcre2);

-	p->pcre2_compile_context = NULL;
+	p->pcre2_general_context = pcre2_general_context_create(pcre2_malloc, pcre2_free, NULL);
+	p->pcre2_compile_context = pcre2_compile_context_create(p->pcre2_general_context);

 	if (opt->ignore_case) {
 		if (has_non_ascii(p->pattern)) {
-			character_tables = pcre2_maketables(NULL);
-			p->pcre2_compile_context = pcre2_compile_context_create(NULL);
+			character_tables = pcre2_maketables(p->pcre2_general_context);
 			pcre2_set_character_tables(p->pcre2_compile_context, character_tables);
 		}
 		options |= PCRE2_CASELESS;
@@ -513,7 +523,7 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 					 p->pcre2_compile_context);

 	if (p->pcre2_pattern) {
-		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, NULL);
+		p->pcre2_match_data = pcre2_match_data_create_from_pattern(p->pcre2_pattern, p->pcre2_general_context);
 		if (!p->pcre2_match_data)
 			die("Couldn't allocate PCRE2 match data");
 	} else {
@@ -550,10 +560,10 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 			return;
 		}

-		p->pcre2_jit_stack = pcre2_jit_stack_create(1, 1024 * 1024, NULL);
+		p->pcre2_jit_stack = pcre2_jit_stack_create(1, 1024 * 1024, p->pcre2_general_context);
 		if (!p->pcre2_jit_stack)
 			die("Couldn't allocate PCRE2 JIT stack");
-		p->pcre2_match_context = pcre2_match_context_create(NULL);
+		p->pcre2_match_context = pcre2_match_context_create(p->pcre2_general_context);
 		if (!p->pcre2_match_context)
 			die("Couldn't allocate PCRE2 match context");
 		pcre2_jit_stack_assign(p->pcre2_match_context, NULL, p->pcre2_jit_stack);
@@ -605,6 +615,7 @@ static void free_pcre2_pattern(struct grep_pat *p)
 	pcre2_match_data_free(p->pcre2_match_data);
 	pcre2_jit_stack_free(p->pcre2_jit_stack);
 	pcre2_match_context_free(p->pcre2_match_context);
+	pcre2_general_context_free(p->pcre2_general_context);
 }
 #else /* !USE_LIBPCRE2 */
 static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
diff --git a/grep.h b/grep.h
index 1875880f37..73b8b87a3a 100644
--- a/grep.h
+++ b/grep.h
@@ -28,6 +28,7 @@ typedef int pcre_jit_stack;
 #else
 typedef int pcre2_code;
 typedef int pcre2_match_data;
+typedef int pcre2_general_context;
 typedef int pcre2_compile_context;
 typedef int pcre2_match_context;
 typedef int pcre2_jit_stack;
@@ -93,6 +94,7 @@ struct grep_pat {
 	int pcre1_jit_on;
 	pcre2_code *pcre2_pattern;
 	pcre2_match_data *pcre2_match_data;
+	pcre2_general_context *pcre2_general_context;
 	pcre2_compile_context *pcre2_compile_context;
 	pcre2_match_context *pcre2_match_context;
 	pcre2_jit_stack *pcre2_jit_stack;
--
2.22.0