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Re: [PATCHv5][PING^3][BZ #17833] _dl_close_worker() does not release inconsistent objects.




On 06/30/2015 06:12 PM, H.J. Lu wrote:
On Tue, Jun 30, 2015 at 7:45 AM, Pavel Kopyl <p.kopyl@samsung.com> wrote:
This patch changes DF_1_NODELETE path.  Do we have a testcase for
sucessfully loading/unloading DF_1_NODELETE DSO with undefined
symbols?

It may have been asked before.  Can we reset unique symbols
in _dl_open before calling _dl_close_worker?

Yes, I added testcases for three possible ways where we can get DF_1_NODELETE:
1. Unique symbols
2. Load with RTLD_NODELETE flag.
3. Link with '-z nodelete' option

>Can we reset unique symbols in _dl_open before calling _dl_close_worker?
But I clear unique symbols exactly in _dl_close_worker.<https://slovari.yandex.ru/exactly/en-ru>


commit eebadd0f414fe6aa5163a184ddae35c57a5fa454
Author: Pavel Kopyl <p.kopyl@samsung.com>
Date:   Fri May 29 20:15:33 2015 +0300

    2015-05-29  Pavel Kopyl  <p.kopyl@samsung.com>
    Mikhail Ilin  <m.ilin@samsung.com>
    
    	[BZ #17833]
    	* elf/Makefile: Add build test commands.
    	* elf/dl-close.c (_dl_close_worker): Implement force object deletion.
    	* elf/dl-open.c (_dl_open): Forced _dl_close_worker call.
    	(_dl_close): Default _dl_close_worker call.
    	* elf/tst-nodelete.cc: Test executable.  New file.
    	* elf/tst-nodeletelib.cc: Test library.  New file.
    	* elf/tst-znodeletelib.cc: Likewise.
    	* include/dlfcn.h (_dl_close_worker): Add new parameter.

diff --git a/elf/Makefile b/elf/Makefile
index dedf3c7..a46eaff 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -131,7 +131,7 @@ tests += $(tests-static)
 ifeq (yes,$(build-shared))
 tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
 	 constload1 order noload filter unload \
-	 reldep reldep2 reldep3 reldep4 nodelete nodelete2 \
+	 reldep reldep2 reldep3 reldep4 nodelete nodelete2 tst-nodelete \
 	 nodlopen nodlopen2 neededtest neededtest2 \
 	 neededtest3 neededtest4 unload2 lateglobal initfirst global \
 	 restest2 next dblload dblunload reldep5 reldep6 reldep7 reldep8 \
@@ -205,7 +205,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-unique1mod1 tst-unique1mod2 \
 		tst-unique2mod1 tst-unique2mod2 \
 		tst-auditmod9a tst-auditmod9b \
-		$(if $(CXX),tst-unique3lib tst-unique3lib2 tst-unique4lib) \
+		$(if $(CXX),tst-unique3lib tst-unique3lib2 tst-unique4lib \
+		  tst-nodelete-uniquemod) \
+		tst-nodelete-rtldmod tst-nodelete-zmod \
 		tst-initordera1 tst-initorderb1 \
 		tst-initordera2 tst-initorderb2 \
 		tst-initordera3 tst-initordera4 \
@@ -592,6 +594,9 @@ ifuncmod5.so-no-z-defs = yes
 ifuncmod6.so-no-z-defs = yes
 tst-auditmod9a.so-no-z-defs = yes
 tst-auditmod9b.so-no-z-defs = yes
+tst-nodelete-uniquemod.so-no-z-defs = yes
+tst-nodelete-rtldmod.so-no-z-defs = yes
+tst-nodelete-zmod.so-no-z-defs = yes
 
 ifeq ($(build-shared),yes)
 # Build all the modules even when not actually running test programs.
@@ -1154,6 +1159,13 @@ $(objpfx)tst-unique3.out: $(objpfx)tst-unique3lib2.so
 
 $(objpfx)tst-unique4: $(objpfx)tst-unique4lib.so
 
+$(objpfx)tst-nodelete: $(libdl)
+$(objpfx)tst-nodelete.out: $(objpfx)tst-nodelete-uniquemod.so \
+			   $(objpfx)tst-nodelete-rtldmod.so \
+			   $(objpfx)tst-nodelete-zmod.so
+
+LDFLAGS-tst-nodelete = -rdynamic
+LDFLAGS-tst-nodelete-zmod.so = -Wl,--enable-new-dtags,-z,nodelete
 $(objpfx)tst-initorder-cmp.out: tst-initorder.exp $(objpfx)tst-initorder.out
 	cmp $^ > $@; \
 	$(evaluate-test)
diff --git a/elf/dl-close.c b/elf/dl-close.c
index 412f71d..0595675 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -108,7 +108,7 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
 
 
 void
-_dl_close_worker (struct link_map *map)
+_dl_close_worker (struct link_map *map, bool force)
 {
   /* One less direct use.  */
   --map->l_direct_opencount;
@@ -152,6 +152,10 @@ _dl_close_worker (struct link_map *map)
       l->l_idx = idx;
       maps[idx] = l;
       ++idx;
+
+      /* clear DF_1_NODELETE to force object deletion.  */
+      if (force)
+	l->l_flags_1 &= ~DF_1_NODELETE;
     }
   assert (idx == nloaded);
 
@@ -635,6 +639,31 @@ _dl_close_worker (struct link_map *map)
 		}
 	    }
 
+	  /* Reset unique symbols if forced.  */
+	  if (force)
+	    {
+	      struct unique_sym_table *tab = &ns->_ns_unique_sym_table;
+	      __rtld_lock_lock_recursive (tab->lock);
+	      struct unique_sym *entries = tab->entries;
+	      if (entries != NULL)
+		{
+		  size_t idx, size = tab->size;
+		  for (idx = 0; idx < size; ++idx)
+		    {
+		      /* Clear unique symbol entries
+		       that belong to this object.  */
+		      if (entries[idx].name != NULL
+			  && entries[idx].map == imap)
+			{
+			  entries[idx].name = NULL;
+			  entries[idx].hashval = 0;
+			  tab->n_elements--;
+			}
+		    }
+		}
+		__rtld_lock_unlock_recursive (tab->lock);
+	    }
+
 	  /* We can unmap all the maps at once.  We determined the
 	     start address and length when we loaded the object and
 	     the `munmap' call does the rest.  */
@@ -782,7 +811,7 @@ _dl_close (void *_map)
   /* Acquire the lock.  */
   __rtld_lock_lock_recursive (GL(dl_load_lock));
 
-  _dl_close_worker (map);
+  _dl_close_worker (map, false);
 
   __rtld_lock_unlock_recursive (GL(dl_load_lock));
 }
diff --git a/elf/dl-open.c b/elf/dl-open.c
index 2d0e082..027c1e0 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -670,7 +670,7 @@ no more namespaces available for dlmopen()"));
 	  if ((mode & __RTLD_AUDIT) == 0)
 	    GL(dl_tls_dtv_gaps) = true;
 
-	  _dl_close_worker (args.map);
+	  _dl_close_worker (args.map, true);
 	}
 
       assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
diff --git a/elf/tst-nodelete-rtldmod.cc b/elf/tst-nodelete-rtldmod.cc
new file mode 100644
index 0000000..740e1d8
--- /dev/null
+++ b/elf/tst-nodelete-rtldmod.cc
@@ -0,0 +1,6 @@
+extern int not_exist (void);
+
+int foo (void)
+{
+  return not_exist ();
+}
diff --git a/elf/tst-nodelete-uniquemod.cc b/elf/tst-nodelete-uniquemod.cc
new file mode 100644
index 0000000..632b303
--- /dev/null
+++ b/elf/tst-nodelete-uniquemod.cc
@@ -0,0 +1,14 @@
+extern int not_exist (void);
+
+inline int make_unique (void)
+{
+  /* Static variables in inline functions and classes
+     generate STB_GNU_UNIQUE symbols.  */
+  static int unique;
+  return ++unique;
+}
+
+int foo (void)
+{
+  return make_unique () + not_exist ();
+}
diff --git a/elf/tst-nodelete-zmod.cc b/elf/tst-nodelete-zmod.cc
new file mode 100644
index 0000000..740e1d8
--- /dev/null
+++ b/elf/tst-nodelete-zmod.cc
@@ -0,0 +1,6 @@
+extern int not_exist (void);
+
+int foo (void)
+{
+  return not_exist ();
+}
diff --git a/elf/tst-nodelete.cc b/elf/tst-nodelete.cc
new file mode 100644
index 0000000..176cb68
--- /dev/null
+++ b/elf/tst-nodelete.cc
@@ -0,0 +1,51 @@
+#include "../dlfcn/dlfcn.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+static int
+do_test (void)
+{
+  int result = 0;
+
+  /* This is a test for correct handling of dlopen failures for library that
+     is loaded with RTLD_NODELETE flag.  The first dlopen should fail because
+     of undefined symbols in shared library.  The second dlopen then verifies
+     that library was properly unloaded.  */
+  if (dlopen ("tst-nodelete-rtldmod.so", RTLD_NOW | RTLD_NODELETE) != NULL
+      || dlopen ("tst-nodelete-rtldmod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
+    {
+      printf ("RTLD_NODELETE test failed\n");
+      result = 1;
+    }
+
+  /* This is a test for correct handling of dlopen failures for library that
+     is linked with '-z nodelete' option and hence has DF_1_NODELETE flag.
+     The first dlopen should fail because of undefined symbols in shared
+     library.  The second dlopen then verifies that library was properly
+     unloaded.  */
+  if (dlopen ("tst-nodelete-zmod.so", RTLD_NOW) != NULL
+      || dlopen ("tst-nodelete-zmod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
+    {
+      printf ("-z nodelete test failed\n");
+      result = 1;
+    }
+
+   /* This is a test for correct handling of dlopen failures for library
+     with unique symbols.  The first dlopen should fail because of undefined
+     symbols in shared library.  The second dlopen then verifies that library
+     was properly unloaded.  */
+  if (dlopen ("tst-nodelete-uniquemod.so", RTLD_NOW) != NULL
+      || dlopen ("tst-nodelete-uniquemod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
+    {
+      printf ("Unique symbols test failed\n");
+      result = 1;
+    }
+
+  if (result == 0)
+    printf ("SUCCESS\n");
+
+  return result;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/elf/tst-znodelete-zlib.cc b/elf/tst-znodelete-zlib.cc
new file mode 100644
index 0000000..1e8f368
--- /dev/null
+++ b/elf/tst-znodelete-zlib.cc
@@ -0,0 +1,6 @@
+extern int not_exist (void);
+
+int foo (void)
+{
+  return  not_exist ();
+}
diff --git a/include/dlfcn.h b/include/dlfcn.h
index a67b2e3..0ce0af5 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -54,7 +54,8 @@ struct link_map;
 extern void _dl_close (void *map) attribute_hidden;
 /* Same as above, but without locking and safety checks for user
    provided map arguments.  */
-extern void _dl_close_worker (struct link_map *map) attribute_hidden;
+extern void _dl_close_worker (struct link_map *map, bool force)
+    attribute_hidden;
 
 /* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
    RTLD_NEXT).  WHO is the calling function, for RTLD_NEXT.  Returns

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