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[RFA] dangling cleanup in find_frame_funname
- From: Keith Seitz <keiths at redhat dot com>
- To: "gdb-patches at sourceware dot org ml" <gdb-patches at sourceware dot org>
- Cc: brobecker at adacore dot com
- Date: Thu, 16 May 2013 12:25:07 -0700
- Subject: [RFA] dangling cleanup in find_frame_funname
[I'm cc'ing Joel on this, since I believe this is the same assertion
failure that he is seeing.]
While testing insight, I ran across the following assertion:
../../gdb/gdb/cleanups.c:264: internal-error: restore_my_cleanups:
Assertion `*pmy_chain == SENTINEL_CLEANUP' failed.
This is caused by a dangling cleanup in find_frame_funname, which uses a
(dangling) cleanup to free memory for the returned function name in some
instances.
I've corrected this by simply requiring the caller to free any memory.
Unfortunately, I don't have a test case to trigger the failure. Perhaps
Joel can describe an ada test case?
This patch definitely needs a few fresh eyeballs...
Keith
ChangeLog
2013-05-16 Keith Seitz <keiths@redhat.com>
* ada-lang.c (is_known_support_routine): Add explicit free of
'func_name' from find_frame_funname.
(ada_unhandled_exception_name_addr_from_raise): Likewise.
* python/py-frame.c (frapy_name): Likewise for 'name'.
* stack.c (find_frame_funname): Add comment explaining that
funcp must be freed by the caller.
Return copy of symbol names instead of pointers.
(print_frame): Add a cleanup for 'funname' from
find_frame_funname.
* stack.h (find_frame_funname): Remove "const" from
'funname' parameter.
diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index fa6db0f..12e5388 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -11105,7 +11105,7 @@ static int
is_known_support_routine (struct frame_info *frame)
{
struct symtab_and_line sal;
- const char *func_name;
+ char *func_name;
enum language func_lang;
int i;
const char *fullname;
@@ -11152,9 +11152,13 @@ is_known_support_routine (struct frame_info *frame)
{
re_comp (known_auxiliary_function_name_patterns[i]);
if (re_exec (func_name))
- return 1;
+ {
+ xfree (func_name);
+ return 1;
+ }
}
+ xfree (func_name);
return 0;
}
@@ -11210,13 +11214,17 @@ ada_unhandled_exception_name_addr_from_raise (void)
while (fi != NULL)
{
- const char *func_name;
+ char *func_name;
enum language func_lang;
find_frame_funname (fi, &func_name, &func_lang, NULL);
if (func_name != NULL
&& strcmp (func_name, data->exception_info->catch_exception_sym) == 0)
- break; /* We found the frame we were looking for... */
+ {
+ xfree (func_name);
+ break; /* We found the frame we were looking for... */
+ }
+ xfree (func_name);
fi = get_prev_frame (fi);
}
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index e2eb9c5..312d26a 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -122,7 +122,7 @@ static PyObject *
frapy_name (PyObject *self, PyObject *args)
{
struct frame_info *frame;
- const char *name;
+ char *name = NULL;
enum language lang;
PyObject *result;
volatile struct gdb_exception except;
@@ -133,10 +133,17 @@ frapy_name (PyObject *self, PyObject *args)
find_frame_funname (frame, &name, &lang, NULL);
}
+
+ if (except.reason < 0)
+ xfree (name);
+
GDB_PY_HANDLE_EXCEPTION (except);
if (name)
- result = PyUnicode_Decode (name, strlen (name), host_charset (), NULL);
+ {
+ result = PyUnicode_Decode (name, strlen (name), host_charset (), NULL);
+ xfree (name);
+ }
else
{
result = Py_None;
diff --git a/gdb/stack.c b/gdb/stack.c
index d10e9b4..a4b392e 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1004,10 +1004,10 @@ get_last_displayed_sal (struct symtab_and_line *sal)
/* Attempt to obtain the FUNNAME, FUNLANG and optionally FUNCP of the function
- corresponding to FRAME. */
+ corresponding to FRAME. FUNNAME needs to be freed by the caller. */
void
-find_frame_funname (struct frame_info *frame, const char **funname,
+find_frame_funname (struct frame_info *frame, char **funname,
enum language *funlang, struct symbol **funcp)
{
struct symbol *func;
@@ -1055,12 +1055,12 @@ find_frame_funname (struct frame_info *frame, const char **funname,
/* We also don't know anything about the function besides
its address and name. */
func = 0;
- *funname = SYMBOL_PRINT_NAME (msymbol.minsym);
+ *funname = xstrdup (SYMBOL_PRINT_NAME (msymbol.minsym));
*funlang = SYMBOL_LANGUAGE (msymbol.minsym);
}
else
{
- *funname = SYMBOL_PRINT_NAME (func);
+ *funname = xstrdup (SYMBOL_PRINT_NAME (func));
*funlang = SYMBOL_LANGUAGE (func);
if (funcp)
*funcp = func;
@@ -1075,8 +1075,8 @@ find_frame_funname (struct frame_info *frame, const char **funname,
if (func_only)
{
+ xfree (*funname);
*funname = func_only;
- make_cleanup (xfree, func_only);
}
}
}
@@ -1092,7 +1092,7 @@ find_frame_funname (struct frame_info *frame, const char **funname,
msymbol = lookup_minimal_symbol_by_pc (pc);
if (msymbol.minsym != NULL)
{
- *funname = SYMBOL_PRINT_NAME (msymbol.minsym);
+ *funname = xstrdup (SYMBOL_PRINT_NAME (msymbol.minsym));
*funlang = SYMBOL_LANGUAGE (msymbol.minsym);
}
}
@@ -1105,7 +1105,7 @@ print_frame (struct frame_info *frame, int print_level,
{
struct gdbarch *gdbarch = get_frame_arch (frame);
struct ui_out *uiout = current_uiout;
- const char *funname = NULL;
+ char *funname = NULL;
enum language funlang = language_unknown;
struct ui_file *stb;
struct cleanup *old_chain, *list_chain;
@@ -1120,6 +1120,7 @@ print_frame (struct frame_info *frame, int print_level,
old_chain = make_cleanup_ui_file_delete (stb);
find_frame_funname (frame, &funname, &funlang, &func);
+ make_cleanup (xfree, funname);
annotate_frame_begin (print_level ? frame_relative_level (frame) : 0,
gdbarch, pc);
diff --git a/gdb/stack.h b/gdb/stack.h
index 841ad43..4badf19 100644
--- a/gdb/stack.h
+++ b/gdb/stack.h
@@ -22,7 +22,7 @@
void select_frame_command (char *level_exp, int from_tty);
-void find_frame_funname (struct frame_info *frame, const char **funname,
+void find_frame_funname (struct frame_info *frame, char **funname,
enum language *funlang, struct symbol **funcp);
typedef void (*iterate_over_block_arg_local_vars_cb) (const char *print_name,