Re: [PATCH] libio: Fix gconv-related memory leak [BZ #24583]

[Florian Weimer <fweimer@redhat.com>]

* Florian Weimer:

> * Andreas Schwab:
>
>> On Mai 20 2019, Florian Weimer <fweimer@redhat.com> wrote:
>>
>>> diff --git a/libio/iofclose.c b/libio/iofclose.c
>>> index 8a80dd0b78..f4c7299db3 100644
>>> --- a/libio/iofclose.c
>>> +++ b/libio/iofclose.c
>>> @@ -61,10 +61,10 @@ _IO_new_fclose (FILE *fp)
>>>  	 the conversion functions.  */
>>>        struct _IO_codecvt *cc = fp->_codecvt;
>>>  
>>> -      __libc_lock_lock (__gconv_lock);
>>> -      __gconv_release_step (cc->__cd_in.__cd.__steps);
>>> -      __gconv_release_step (cc->__cd_out.__cd.__steps);
>>> -      __libc_lock_unlock (__gconv_lock);
>>> +      __gconv_close_transform (cc->__cd_in.__cd.__steps,
>>> +			       cc->__cd_in.__cd.__nsteps);
>>> +      __gconv_close_transform (cc->__cd_out.__cd.__steps,
>>> +			       cc->__cd_out.__cd.__nsteps);
>>
>> Are the __steps always allocated?  In get_gconv_fcts I see them being
>> set to static data.
>
> Correct, this needs to be handled differently.  It is difficult to
> reproduce because the test framework disables the gconv cache (even when
> running in a container).
>
> I will try to fix the test framework first.

I've already posted the sbindir patch and the test-in-container fix.

The patch below should fix the memory leak, while avoiding the static
allocation issue you've identified.  Ideally, we would use struct
gconv_fcts in libio as well, but I think that's best handled as a
separate cleanup, after the codecvt vtable removal.

Thanks,
Florian

libio: Fix gconv-related memory leak [BZ #24583]

struct gconv_fcts for the C locale is statically allocated,
and __gconv_close_transform deallocates the steps object.
Therefore this commit introduces __wcsmbs_close_conv to avoid
freeing the statically allocated step objects.

2019-05-20  Florian Weimer  <fweimer@redhat.com>

	[BZ #24583]
	* wcsmbs/wcsmbsload.h (__wcsmbs_close_conv): Declare.
	* wcsmbs/wcsmbsload.c (__wcsmbs_close_conv): Define.
	* libio/iofclose.c (_IO_new_fclose): Call __wcsmbs_close_conv
	instead of __gconv_release_step.
	* libio/Makefile (tests): Add tst-wfile-gconv.
	(tests-container): Add tst-wfile-ascii.
	(tst-wfile-gconv-ENV): Enable mtrace.
	(generated): Add tst-wfile-gconv.mtrace, tst-wfile-gconv.check.
	(tests-special): Add tst-wfile-gconv-mem.out.
	(tst-wfile-gconv.out): Depend on locales.
	(tst-wfile-gconv-mem.out): Add mtrace rule.
	* libio/tst-wfile-ascii.c: New file.
	* libio/tst-wfile-gconv.c: Likewise.

diff --git a/libio/Makefile b/libio/Makefile
index a5236c7042..7d53cb06b0 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -66,7 +66,11 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc   \
 	tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \
 	tst-ftell-append tst-fputws tst-bz22415 tst-fgetc-after-eof \
 	tst-sprintf-ub tst-sprintf-chk-ub tst-bz24051 tst-bz24153 \
-	tst-wfile-sync
+	tst-wfile-sync tst-wfile-gconv
+
+# This test tests interaction with the gconv cache.  Setting
+# GCONV_CACHE during out-of-container testing disables the cache.
+tests-container += tst-wfile-ascii
 
 tests-internal = tst-vtables tst-vtables-interposed tst-readline
 
@@ -163,10 +167,12 @@ tst_wprintf2-ARGS = "Some Text"
 test-fmemopen-ENV = MALLOC_TRACE=$(objpfx)test-fmemopen.mtrace
 tst-fopenloc-ENV = MALLOC_TRACE=$(objpfx)tst-fopenloc.mtrace
 tst-bz22415-ENV = MALLOC_TRACE=$(objpfx)tst-bz22415.mtrace
+tst-wfile-gconv-ENV = MALLOC_TRACE=$(objpfx)tst-wfile-gconv.mtrace
 
 generated += test-fmemopen.mtrace test-fmemopen.check
 generated += tst-fopenloc.mtrace tst-fopenloc.check
 generated += tst-bz22415.mtrace tst-bz22415.check
+generated += tst-wfile-gconv.mtrace tst-wfile-gconv.check
 
 aux	:= fileops genops stdfiles stdio strops
 
@@ -181,7 +187,8 @@ shared-only-routines = oldiofopen oldiofdopen oldiofclose oldfileops	\
 
 ifeq ($(run-built-tests),yes)
 tests-special += $(objpfx)test-freopen.out $(objpfx)test-fmemopen-mem.out \
-		 $(objpfx)tst-bz22415-mem.out
+		 $(objpfx)tst-bz22415-mem.out \
+		 $(objpfx)tst-wfile-gconv-mem.out
 ifeq (yes,$(build-shared))
 # Run tst-fopenloc-cmp.out and tst-openloc-mem.out only if shared
 # library is enabled since they depend on tst-fopenloc.out.
@@ -214,6 +221,7 @@ $(objpfx)tst-ungetwc2.out: $(gen-locales)
 $(objpfx)tst-widetext.out: $(gen-locales)
 $(objpfx)tst_wprintf2.out: $(gen-locales)
 $(objpfx)tst-wfile-sync.out: $(gen-locales)
+$(objpfx)tst-wfile-gconv.out: $(gen-locales)
 endif
 
 $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen
@@ -237,3 +245,7 @@ $(objpfx)tst-fopenloc-mem.out: $(objpfx)tst-fopenloc.out
 $(objpfx)tst-bz22415-mem.out: $(objpfx)tst-bz22415.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-bz22415.mtrace > $@; \
 	$(evaluate-test)
+
+$(objpfx)tst-wfile-gconv-mem.out: $(objpfx)tst-wfile-gconv.out
+	$(common-objpfx)malloc/mtrace $(objpfx)tst-wfile-gconv.mtrace > $@; \
+	$(evaluate-test)
diff --git a/libio/iofclose.c b/libio/iofclose.c
index 8a80dd0b78..c03c6cf57c 100644
--- a/libio/iofclose.c
+++ b/libio/iofclose.c
@@ -26,8 +26,8 @@
 
 #include "libioP.h"
 #include <stdlib.h>
-#include "../iconv/gconv_int.h"
 #include <shlib-compat.h>
+#include <wcsmbs/wcsmbsload.h>
 
 int
 _IO_new_fclose (FILE *fp)
@@ -60,11 +60,14 @@ _IO_new_fclose (FILE *fp)
       /* This stream has a wide orientation.  This means we have to free
 	 the conversion functions.  */
       struct _IO_codecvt *cc = fp->_codecvt;
-
-      __libc_lock_lock (__gconv_lock);
-      __gconv_release_step (cc->__cd_in.__cd.__steps);
-      __gconv_release_step (cc->__cd_out.__cd.__steps);
-      __libc_lock_unlock (__gconv_lock);
+      struct gconv_fcts conv =
+	{
+	 .towc = cc->__cd_in.__cd.__steps,
+	 .towc_nsteps = cc->__cd_in.__cd.__nsteps,
+	 .tomb = cc->__cd_out.__cd.__steps,
+	 .tomb_nsteps = cc->__cd_out.__cd.__nsteps,
+	};
+      __wcsmbs_close_conv (&conv);
     }
   else
     {
diff --git a/libio/tst-wfile-ascii.c b/libio/tst-wfile-ascii.c
new file mode 100644
index 0000000000..77272fc125
--- /dev/null
+++ b/libio/tst-wfile-ascii.c
@@ -0,0 +1,51 @@
+/* Test ASCII gconv module followed by cache initialization.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xstdio.h>
+#include <wchar.h>
+
+static int
+do_test (void)
+{
+  /* Create the gconv module cache.  iconvconfig is in /sbin, which is
+     not on PATH.  */
+  {
+    char *iconvconfig = xasprintf ("%s/iconvconfig", support_sbindir_prefix);
+    TEST_COMPARE (system (iconvconfig), 0);
+  }
+
+  /* Use built-in ASCII gconv module, without triggering cache
+     initialization.  */
+  FILE *fp1 = xfopen ("/dev/zero", "r");
+  TEST_COMPARE (fwide (fp1, 1), 1);
+
+  /* Use non-ASCII gconv module and trigger gconv cache
+     initialization.  */
+  FILE *fp2 = xfopen ("/dev/zero", "r,ccs=UTF-8");
+  TEST_COMPARE (fwide (fp2, 0), 1);
+
+  xfclose (fp1);
+  xfclose (fp2);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/libio/tst-wfile-gconv.c b/libio/tst-wfile-gconv.c
new file mode 100644
index 0000000000..de603b32d2
--- /dev/null
+++ b/libio/tst-wfile-gconv.c
@@ -0,0 +1,36 @@
+/* Test that non-built-in gconv modules do not cause memory leak (bug 24583).
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <locale.h>
+#include <mcheck.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+static int
+do_test (void)
+{
+  mtrace ();
+
+  TEST_VERIFY_EXIT (setlocale (LC_ALL, "ja_JP.EUC-JP") != NULL);
+  xfclose (xfopen ("/etc/passwd", "r,ccs=UTF-8"));
+  xfclose (xfopen ("/etc/passwd", "r"));
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/wcsmbs/wcsmbsload.c b/wcsmbs/wcsmbsload.c
index 5494d0a23e..cff7ca85f9 100644
--- a/wcsmbs/wcsmbsload.c
+++ b/wcsmbs/wcsmbsload.c
@@ -265,3 +265,17 @@ _nl_cleanup_ctype (struct __locale_data *locale)
       free ((char *) data);
     }
 }
+
+/* Free the specified conversion functions (but not CONV itself).  */
+void
+__wcsmbs_close_conv (struct gconv_fcts *conv)
+{
+  /* Nothing to do if both conversions are statically allocated.  */
+  if (conv->towc == &to_wc && conv->tomb == &to_mb)
+    return;
+
+  if (conv->towc != &to_wc)
+      __gconv_close_transform (conv->towc, conv->towc_nsteps);
+  if (conv->tomb != &to_mb)
+      __gconv_close_transform (conv->tomb, conv->tomb_nsteps);
+}
diff --git a/wcsmbs/wcsmbsload.h b/wcsmbs/wcsmbsload.h
index 6ccad4b3ba..c2fffbd914 100644
--- a/wcsmbs/wcsmbsload.h
+++ b/wcsmbs/wcsmbsload.h
@@ -51,6 +51,7 @@ extern int __wcsmbs_named_conv (struct gconv_fcts *copy, const char *name)
 /* Function used for the `private.cleanup' hook.  */
 extern void _nl_cleanup_ctype (struct __locale_data *) attribute_hidden;
 
+extern void __wcsmbs_close_conv (struct gconv_fcts *conv) attribute_hidden;
 
 #include <iconv/gconv_int.h>