Re: building/using address-sanitizer-enabled emacs?

[Paul Eggert <eggert@cs.ucla.edu>]

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On 05/09/2017 07:41 PM, Eli Zaretskii wrote:
>> From: Jim Meyering<jim@meyering.net>
>> With the above, I thought I was avoiding the undumping issue by using temacs.
> Indeed, I believe the problem you reported is unrelated to unexec.

You're right, I didn't read Jim's message carefully enough. I see that 
the AddressSanitizer code suffered some bitrot since I last got it 
working; among other things its output was being discarded on Fedora 25 
x86-64, which at first gave me a false sense of security.... I installed 
the attached patches to work around the GCC problem that Jim reported, 
the improper output discard, and one minor memory leak uncovered by 
AddressSanitizer.  When I run Emacs with AddressSanitizer now, it 
reports some other minor memory leaks, almost all from the fontconfig 
library. I do not observe any problems with SAFE_ALLOCA.


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From be9e60fc3c43cc49cc5d749924c3e96737ae297c Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 16 May 2017 14:29:18 -0700
Subject: [PATCH 1/3] Simplify procname code to avoid GCC bug

* src/process.c (server_accept_connection): Simplify and avoid
multiple calls and struct literals in the last case of a switch.
The old code ran afoul of GCC bug 80659, which caused an internal
compiler error.  Problem reported by Jim Meyering in:
http://lists.gnu.org/archive/html/emacs-devel/2017-05/msg00182.html
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80659
---
 src/process.c | 53 ++++++++++++++++++++++++-----------------------------
 1 file changed, 24 insertions(+), 29 deletions(-)

diff --git a/src/process.c b/src/process.c
index 4a28639..fdea977 100644
--- a/src/process.c
+++ b/src/process.c
@@ -4659,7 +4659,7 @@ static EMACS_INT connect_counter = 0;
 static void
 server_accept_connection (Lisp_Object server, int channel)
 {
-  Lisp_Object proc, caller, name, buffer;
+  Lisp_Object buffer;
   Lisp_Object contact, host, service;
   struct Lisp_Process *ps = XPROCESS (server);
   struct Lisp_Process *p;
@@ -4701,49 +4701,43 @@ server_accept_connection (Lisp_Object server, int channel)
      information for this process.  */
   host = Qt;
   service = Qnil;
+  Lisp_Object args[11];
+  int nargs = 0;
+  AUTO_STRING (procname_format_in, "%s <%d.%d.%d.%d:%d>");
+  AUTO_STRING (procname_format_in6, "%s <[%x:%x:%x:%x:%x:%x:%x:%x]:%d>");
+  AUTO_STRING (procname_format_default, "%s <%d>");
   switch (saddr.sa.sa_family)
     {
     case AF_INET:
       {
+	args[nargs++] = procname_format_in;
+	nargs++;
 	unsigned char *ip = (unsigned char *)&saddr.in.sin_addr.s_addr;
-
-	AUTO_STRING (ipv4_format, "%d.%d.%d.%d");
-	host = CALLN (Fformat, ipv4_format,
-		      make_number (ip[0]), make_number (ip[1]),
-		      make_number (ip[2]), make_number (ip[3]));
 	service = make_number (ntohs (saddr.in.sin_port));
-	AUTO_STRING (caller_format, " <%s:%d>");
-	caller = CALLN (Fformat, caller_format, host, service);
+	for (int i = 0; i < 4; i++)
+	  args[nargs++] = make_number (ip[i]);
+	args[nargs++] = service;
       }
       break;
 
 #ifdef AF_INET6
     case AF_INET6:
       {
-	Lisp_Object args[9];
+	args[nargs++] = procname_format_in6;
+	nargs++;
 	uint16_t *ip6 = (uint16_t *)&saddr.in6.sin6_addr;
-	int i;
-
-	AUTO_STRING (ipv6_format, "%x:%x:%x:%x:%x:%x:%x:%x");
-	args[0] = ipv6_format;
-	for (i = 0; i < 8; i++)
-	  args[i + 1] = make_number (ntohs (ip6[i]));
-	host = CALLMANY (Fformat, args);
 	service = make_number (ntohs (saddr.in.sin_port));
-	AUTO_STRING (caller_format, " <[%s]:%d>");
-	caller = CALLN (Fformat, caller_format, host, service);
+	for (int i = 0; i < 8; i++)
+	  args[nargs++] = make_number (ip6[i]);
+	args[nargs++] = service;
       }
       break;
 #endif
 
-#ifdef HAVE_LOCAL_SOCKETS
-    case AF_LOCAL:
-#endif
     default:
-      caller = Fnumber_to_string (make_number (connect_counter));
-      AUTO_STRING (space_less_than, " <");
-      AUTO_STRING (greater_than, ">");
-      caller = concat3 (space_less_than, caller, greater_than);
+      args[nargs++] = procname_format_default;
+      nargs++;
+      args[nargs++] = make_number (connect_counter);
       break;
     }
 
@@ -4764,16 +4758,17 @@ server_accept_connection (Lisp_Object server, int channel)
 	buffer = ps->name;
       if (!NILP (buffer))
 	{
-	  buffer = concat2 (buffer, caller);
-	  buffer = Fget_buffer_create (buffer);
+	  args[1] = buffer;
+	  buffer = Fget_buffer_create (Fformat (nargs, args));
 	}
     }
 
   /* Generate a unique name for the new server process.  Combine the
      server process name with the caller identification.  */
 
-  name = concat2 (ps->name, caller);
-  proc = make_process (name);
+  args[1] = ps->name;
+  Lisp_Object name = Fformat (nargs, args);
+  Lisp_Object proc = make_process (name);
 
   chan_process[s] = proc;
 
-- 
2.9.4


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From 69d0a8500cabc4c034e2d6d873af54a8e8362e3b Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 16 May 2017 14:30:37 -0700
Subject: [PATCH 2/3] Do not discard AddressSanitizer stderr

* src/emacs.c (close_output_streams) [ADDRESS_SANITIZER]:
Do not close stderr.
---
 src/emacs.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/emacs.c b/src/emacs.c
index 9339d60..3aa914f 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -657,8 +657,11 @@ close_output_streams (void)
       _exit (EXIT_FAILURE);
     }
 
-   if (close_stream (stderr) != 0)
-     _exit (EXIT_FAILURE);
+  /* Do not close stderr if addresses are being sanitized, as the
+     sanitizer might report to stderr after this function is
+     invoked.  */
+  if (!ADDRESS_SANITIZER && close_stream (stderr) != 0)
+    _exit (EXIT_FAILURE);
 }
 
 /* ARGSUSED */
-- 
2.9.4


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From f7c07930b581b1bcfdfb1874b6883233516bdf11 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 16 May 2017 14:19:36 -0700
Subject: [PATCH 3/3] Fix minor timezone memory leak

* src/editfns.c (wall_clock_tz): Remove; unused.
---
 src/editfns.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/editfns.c b/src/editfns.c
index ecb8e3f..75eb75a 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -81,10 +81,8 @@ static Lisp_Object styled_format (ptrdiff_t, Lisp_Object *, bool);
 
 enum { tzeqlen = sizeof "TZ=" - 1 };
 
-/* Time zones equivalent to current local time, to wall clock time,
-   and to UTC, respectively.  */
+/* Time zones equivalent to current local time and to UTC, respectively.  */
 static timezone_t local_tz;
-static timezone_t wall_clock_tz;
 static timezone_t const utc_tz = 0;
 
 /* The cached value of Vsystem_name.  This is used only to compare it
@@ -269,7 +267,6 @@ init_editfns (bool dumping)
 
   /* Set the time zone rule now, so that the call to putenv is done
      before multiple threads are active.  */
-  wall_clock_tz = xtzalloc (0);
   tzlookup (tz ? build_string (tz) : Qwall, true);
 
   pw = getpwuid (getuid ());
-- 
2.9.4