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[PATCH] dlfcn: do not mark dlopen/dlclose as leaf functions


Since the dlopen funcs might invoke a constructor that is in the same
compilation unit as the caller, we cannot mark them as leaf funcs.

Similarly, dlclose might invoke a destructor that is in the same
compilation unit as the caller.

Reportedy-by: Fabrice Bauzac <libnoon@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2013-08-26  Mike Frysinger  <vapier@gentoo.org>

	* dlfcn/Makefile (tests): Add bug-dl-leaf.
	(modules-names): Add bug-dl-leaf-lib and bug-dl-leaf-lib-cb.
	($(objpfx)bug-dl-leaf): New rule.
	($(objpfx)bug-dl-leaf.so): Likewise.
	* dlfcn/bug-dl-leaf.c: New test.
	* dlfcn/bug-dl-leaf-lib.c: Likewise.
	* dlfcn/bug-dl-leaf-lib-cb.c: Likewise.
	* dlfcn/dlfcn.h (dlopen): Change __THROW to __THROWNL.
	(dlclose): Likewise.
	(dlmopen): Likewise.
---
 dlfcn/Makefile             |  8 +++++--
 dlfcn/bug-dl-leaf-lib-cb.c | 17 ++++++++++++++
 dlfcn/bug-dl-leaf-lib.c    | 56 ++++++++++++++++++++++++++++++++++++++++++++++
 dlfcn/bug-dl-leaf.c        |  9 ++++++++
 dlfcn/dlfcn.h              |  6 ++---
 5 files changed, 91 insertions(+), 5 deletions(-)
 create mode 100644 dlfcn/bug-dl-leaf-lib-cb.c
 create mode 100644 dlfcn/bug-dl-leaf-lib.c
 create mode 100644 dlfcn/bug-dl-leaf.c

diff --git a/dlfcn/Makefile b/dlfcn/Makefile
index 57a7271..eaf6ddd 100644
--- a/dlfcn/Makefile
+++ b/dlfcn/Makefile
@@ -35,12 +35,13 @@ endif
 ifeq (yes,$(build-shared))
 tests = glrefmain failtest tst-dladdr default errmsg1 tstcxaatexit \
 	bug-dlopen1 bug-dlsym1 tst-dlinfo bug-atexit1 bug-atexit2 \
-	bug-atexit3 tstatexit
+	bug-atexit3 tstatexit bug-dl-leaf
 endif
 modules-names = glreflib1 glreflib2 glreflib3 failtestmod defaultmod1 \
 		defaultmod2 errmsg1mod modatexit modcxaatexit \
 		bug-dlsym1-lib1 bug-dlsym1-lib2 bug-atexit1-lib \
-		bug-atexit2-lib bug-atexit3-lib
+		bug-atexit2-lib bug-atexit3-lib bug-dl-leaf-lib \
+		bug-dl-leaf-lib-cb
 
 failtestmod.so-no-z-defs = yes
 glreflib2.so-no-z-defs = yes
@@ -132,3 +133,6 @@ $(objpfx)bug-atexit2.out: $(objpfx)bug-atexit2-lib.so
 LDLIBS-bug-atexit3-lib.so = -lstdc++ -lgcc_eh
 $(objpfx)bug-atexit3: $(libdl)
 $(objpfx)bug-atexit3.out: $(objpfx)bug-atexit3-lib.so
+
+$(objpfx)bug-dl-leaf: $(libdl) $(objpfx)bug-dl-leaf-lib.so
+$(objpfx)bug-dl-leaf.out: $(objpfx)bug-dl-leaf-lib-cb.so
diff --git a/dlfcn/bug-dl-leaf-lib-cb.c b/dlfcn/bug-dl-leaf-lib-cb.c
new file mode 100644
index 0000000..0af12fc
--- /dev/null
+++ b/dlfcn/bug-dl-leaf-lib-cb.c
@@ -0,0 +1,17 @@
+/* Make sure dlopen/dlclose are not marked as leaf functions.
+ * See bug-dl-leaf-lib.c for details.  */
+
+extern void check_val_init (void);
+extern void check_val_fini (void);
+
+__attribute__ ((__constructor__))
+void construct (void)
+{
+  check_val_init ();
+}
+
+__attribute__ ((__destructor__))
+void destruct (void)
+{
+  check_val_fini ();
+}
diff --git a/dlfcn/bug-dl-leaf-lib.c b/dlfcn/bug-dl-leaf-lib.c
new file mode 100644
index 0000000..88a04f6
--- /dev/null
+++ b/dlfcn/bug-dl-leaf-lib.c
@@ -0,0 +1,56 @@
+/* Make sure dlopen/dlclose are not marked as leaf functions.
+ *
+ * The bug-dl-leaf.c file will call our lib_main directly.  We do this to
+ * keep things simple -- no need to use --export-dynamic with the linker
+ * or build the main ELF as a PIE.
+ *
+ * The lib_main func will modify some of its state while dlopening and
+ * dlclosing the bug-dl-leaf-lib-cb.so library.  The constructors and
+ * destructors in that library will call back into this library to also
+ * muck with state (the check_val_* funcs).
+ *
+ * If dlclose/dlopen are marked as "leaf" functions, then with newer
+ * versions of gcc, the state modification won't work correctly.
+ *
+ * Test by Mike Frysinger <vapier@gentoo.org>
+ */
+
+#include <assert.h>
+#include <dlfcn.h>
+
+static int val = 1;
+static int called = 0;
+
+void check_val_init (void)
+{
+  called = 1;
+  assert (val == 2);
+}
+
+void check_val_fini (void)
+{
+  called = 2;
+  assert (val == 4);
+}
+
+int lib_main (void)
+{
+  int ret;
+  void *hdl;
+
+  /* Make sure the constructor sees the updated val.  */
+  val = 2;
+  hdl = dlopen ("bug-dl-leaf-lib-cb.so", RTLD_GLOBAL | RTLD_LAZY);
+  val = 3;
+  assert (hdl);
+  assert (called == 1);
+
+  /* Make sure the destructor sees the updated val.  */
+  val = 4;
+  ret = dlclose (hdl);
+  val = 5;
+  assert (ret == 0);
+  assert (called == 2);
+
+  return !val;
+}
diff --git a/dlfcn/bug-dl-leaf.c b/dlfcn/bug-dl-leaf.c
new file mode 100644
index 0000000..bea14ab
--- /dev/null
+++ b/dlfcn/bug-dl-leaf.c
@@ -0,0 +1,9 @@
+/* Make sure dlopen/dlclose are not marked as leaf functions.
+ * See bug-dl-leaf-lib.c for details.  */
+
+extern int lib_main (void);
+
+int main (void)
+{
+  return lib_main ();
+}
diff --git a/dlfcn/dlfcn.h b/dlfcn/dlfcn.h
index 241b554..1ed47b1 100644
--- a/dlfcn/dlfcn.h
+++ b/dlfcn/dlfcn.h
@@ -53,11 +53,11 @@ __BEGIN_DECLS
 
 /* Open the shared object FILE and map it in; return a handle that can be
    passed to `dlsym' to get symbol values from it.  */
-extern void *dlopen (const char *__file, int __mode) __THROW;
+extern void *dlopen (const char *__file, int __mode) __THROWNL;
 
 /* Unmap and close a shared object opened by `dlopen'.
    The handle cannot be used again after calling `dlclose'.  */
-extern int dlclose (void *__handle) __THROW __nonnull ((1));
+extern int dlclose (void *__handle) __THROWNL __nonnull ((1));
 
 /* Find the run-time address in the shared object HANDLE refers to
    of the symbol called NAME.  */
@@ -66,7 +66,7 @@ extern void *dlsym (void *__restrict __handle,
 
 #ifdef __USE_GNU
 /* Like `dlopen', but request object to be allocated in a new namespace.  */
-extern void *dlmopen (Lmid_t __nsid, const char *__file, int __mode) __THROW;
+extern void *dlmopen (Lmid_t __nsid, const char *__file, int __mode) __THROWNL;
 
 /* Find the run-time address in the shared object HANDLE refers to
    of the symbol called NAME with VERSION.  */
-- 
1.8.3.2


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