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PR23938, should not free memory alloced in obstack by free() 

This removes ineffectual and wrong code caching section names in
gas/stabs.c.  Code like

  seg = subseg_new (name, 0);
  ...
  if (seg->name == name)
    seg->name = xstrdup (name);

with the idea of being able to unconditionally free "name" later no
longer works.  "name" is referenced by the section hash table as well
as in the section->name field.  It would be possible to use
"bfd_rename_section (stdoutput, seg, xstrdup (name))", but instead I
opted for a fairly straight-forward approach of adding extra
parameters to two functions to indicate section name strings should be
freed if possible.

	PR 23938
	* read.h (get_stab_string_offset): Update prototype.
	* stabs.c (get_stab_string_offset): Add free_stabstr_secname
	parameter.  Free stabstr_secname if unused as section name.
	Don't xstrdup name when used.
	(s_stab_generic): Remove forward declaration.  Add
	stab_secname_obstack_end param.  Reference notes obstack via
	macros.  Delete cached_secname.  Adjust get_stab_string_offset
	call.  Free stab_secname if unused as section name.
	(s_stab): Adjust s_stab_generic call.
	(s_xstab): Likewise.  Delete saved_secname and saved_strsecname.
	* config/obj-elf.c (obj_elf_init_stab_section): Adjust
	get_stab_string_offset call.
	* config/obj-coff.c (obj_coff_init_stab_section): Likewise.
	* config/obj-som.c (obj_som_init_stab_section): Likewise.
	* testsuite/gas/all/pr23938.s: New test.
	* testsuite/gas/all/gas.exp: Run it.
This commit is contained in:
Alan Modra 2018-12-01 09:37:48 +10:30
parent 35d1b0784a
commit 0acc7632bb
8 changed files with 67 additions and 44 deletions
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20
gas/ChangeLog
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@ -1,3 +1,23 @@
2018-12-01 Alan Modra <amodra@gmail.com>
PR 23938
* read.h (get_stab_string_offset): Update prototype.
* stabs.c (get_stab_string_offset): Add free_stabstr_secname
parameter. Free stabstr_secname if unused as section name.
Don't xstrdup name when used.
(s_stab_generic): Remove forward declaration. Add
stab_secname_obstack_end param. Reference notes obstack via
macros. Delete cached_secname. Adjust get_stab_string_offset
call. Free stab_secname if unused as section name.
(s_stab): Adjust s_stab_generic call.
(s_xstab): Likewise. Delete saved_secname and saved_strsecname.
* config/obj-elf.c (obj_elf_init_stab_section): Adjust
get_stab_string_offset call.
* config/obj-coff.c (obj_coff_init_stab_section): Likewise.
* config/obj-som.c (obj_som_init_stab_section): Likewise.
* testsuite/gas/all/pr23938.s: New test.
* testsuite/gas/all/gas.exp: Run it.
2018-11-30 Fredrik Noring <noring@nocrew.org>
* config/tc-mips.c (mips_fix_r5900, mips_fix_r5900_explicit):

2
gas/config/obj-coff.c
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@ -1802,7 +1802,7 @@ obj_coff_init_stab_section (segT seg)
memset (p, 0, 12);
file = as_where ((unsigned int *) NULL);
stabstr_name = concat (seg->name, "str", (char *) NULL);
stroff = get_stab_string_offset (file, stabstr_name);
stroff = get_stab_string_offset (file, stabstr_name, TRUE);
know (stroff == 1);
md_number_to_chars (p, stroff, 4);
}

2
gas/config/obj-elf.c
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@ -2127,7 +2127,7 @@ obj_elf_init_stab_section (segT seg)
memset (p, 0, 12);
file = as_where (NULL);
stabstr_name = concat (segment_name (seg), "str", (char *) NULL);
stroff = get_stab_string_offset (file, stabstr_name);
stroff = get_stab_string_offset (file, stabstr_name, TRUE);
know (stroff == 1 || (stroff == 0 && file[0] == '\0'));
md_number_to_chars (p, stroff, 4);
seg_info (seg)->stabu.p = p;

2
gas/config/obj-som.c
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@ -243,7 +243,7 @@ obj_som_init_stab_section (segT seg)
p = frag_more (12);
memset (p, 0, 12);
file = as_where ((unsigned int *) NULL);
stroff = get_stab_string_offset (file, "$GDB_STRINGS$");
stroff = get_stab_string_offset (file, "$GDB_STRINGS$", FALSE);
know (stroff == 1);
md_number_to_chars (p, stroff, 4);
seg_info (seg)->stabu.p = p;

2
gas/read.h
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@ -114,7 +114,7 @@ extern char original_case_string[];
extern void pop_insert (const pseudo_typeS *);
extern unsigned int get_stab_string_offset
(const char *string, const char *stabstr_secname);
(const char *, const char *, bfd_boolean);
extern void aout_process_stab (int, const char *, int, int, int);
extern char *demand_copy_string (int *lenP);
extern char *demand_copy_C_string (int *len_pointer);

79
gas/stabs.c
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@ -34,7 +34,6 @@
int outputting_stabs_line_debug = 0;
static void s_stab_generic (int, const char *, const char *);
static void generate_asm_file (int, const char *);
/* Allow backends to override the names used for the stab sections. */
@ -80,7 +79,8 @@ static const char *current_function_label;
#endif
unsigned int
get_stab_string_offset (const char *string, const char *stabstr_secname)
get_stab_string_offset (const char *string, const char *stabstr_secname,
bfd_boolean free_stabstr_secname)
{
unsigned int length;
unsigned int retval;
@ -97,8 +97,10 @@ get_stab_string_offset (const char *string, const char *stabstr_secname)
save_seg = now_seg;
save_subseg = now_subseg;
/* Create the stab string section. */
/* Create the stab string section, if it doesn't already exist. */
seg = subseg_new (stabstr_secname, 0);
if (free_stabstr_secname && seg->name != stabstr_secname)
free ((char *) stabstr_secname);
retval = seg_info (seg)->stabu.stab_string_size;
if (retval <= 0)
@ -108,8 +110,6 @@ get_stab_string_offset (const char *string, const char *stabstr_secname)
*p = 0;
retval = seg_info (seg)->stabu.stab_string_size = 1;
bfd_set_section_flags (stdoutput, seg, SEC_READONLY | SEC_DEBUGGING);
if (seg->name == stabstr_secname)
seg->name = xstrdup (stabstr_secname);
}
if (length > 0)
@ -170,12 +170,15 @@ aout_process_stab (int what, const char *string, int type, int other, int desc)
#endif
/* This can handle different kinds of stabs (s,n,d) and different
kinds of stab sections. */
kinds of stab sections. If STAB_SECNAME_OBSTACK_END is non-NULL,
then STAB_SECNAME and STABSTR_SECNAME will be freed if possible
before this function returns (the former by obstack_free). */
static void
s_stab_generic (int what,
const char * stab_secname,
const char * stabstr_secname)
s_stab_generic (int what,
const char *stab_secname,
const char *stabstr_secname,
const char *stab_secname_obstack_end)
{
long longint;
const char *string;
@ -211,7 +214,7 @@ s_stab_generic (int what,
/* FIXME: We should probably find some other temporary storage
for string, rather than leaking memory if someone else
happens to use the notes obstack. */
saved_string_obstack_end = notes.next_free;
saved_string_obstack_end = obstack_next_free (&notes);
SKIP_WHITESPACE ();
if (*input_line_pointer == ',')
input_line_pointer++;
@ -313,7 +316,6 @@ s_stab_generic (int what,
char *p;
static segT cached_sec;
static char *cached_secname;
dot = frag_now_fix ();
@ -321,7 +323,7 @@ s_stab_generic (int what,
md_flush_pending_output ();
#endif
if (cached_secname && !strcmp (cached_secname, stab_secname))
if (cached_sec && strcmp (cached_sec->name, stab_secname) == 0)
{
seg = cached_sec;
subseg_set (seg, 0);
@ -329,9 +331,6 @@ s_stab_generic (int what,
else
{
seg = subseg_new (stab_secname, 0);
if (cached_secname)
free (cached_secname);
cached_secname = xstrdup (stab_secname);
cached_sec = seg;
}
@ -345,13 +344,19 @@ s_stab_generic (int what,
seg_info (seg)->hadone = 1;
}
stroff = get_stab_string_offset (string, stabstr_secname);
if (what == 's')
{
/* Release the string, if nobody else has used the obstack. */
if (saved_string_obstack_end == notes.next_free)
obstack_free (&notes, string);
}
stroff = get_stab_string_offset (string, stabstr_secname,
stab_secname_obstack_end != NULL);
/* Release the string, if nobody else has used the obstack. */
if (saved_string_obstack_end != NULL
&& saved_string_obstack_end == obstack_next_free (&notes))
obstack_free (&notes, string);
/* Similarly for the section name. This must be done before
creating symbols below, which uses the notes obstack. */
if (seg->name != stab_secname
&& stab_secname_obstack_end != NULL
&& stab_secname_obstack_end == obstack_next_free (&notes))
obstack_free (&notes, stab_secname);
/* At least for now, stabs in a special stab section are always
output as 12 byte blocks of information. */
@ -390,6 +395,12 @@ s_stab_generic (int what,
}
else
{
if (stab_secname_obstack_end != NULL)
{
free ((char *) stabstr_secname);
if (stab_secname_obstack_end == obstack_next_free (&notes))
obstack_free (&notes, stab_secname);
}
#ifdef OBJ_PROCESS_STAB
OBJ_PROCESS_STAB (0, what, string, type, other, desc);
#else
@ -405,7 +416,7 @@ s_stab_generic (int what,
void
s_stab (int what)
{
s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME, NULL);
}
/* "Extended stabs", used in Solaris only now. */
@ -414,13 +425,10 @@ void
s_xstab (int what)
{
int length;
char *stab_secname, *stabstr_secname;
static char *saved_secname, *saved_strsecname;
char *stab_secname, *stabstr_secname, *stab_secname_obstack_end;
/* @@ MEMORY LEAK: This allocates a copy of the string, but in most
cases it will be the same string, so we could release the storage
back to the obstack it came from. */
stab_secname = demand_copy_C_string (&length);
stab_secname_obstack_end = obstack_next_free (&notes);
SKIP_WHITESPACE ();
if (*input_line_pointer == ',')
input_line_pointer++;
@ -433,18 +441,9 @@ s_xstab (int what)
/* To get the name of the stab string section, simply add "str" to
the stab section name. */
if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
{
stabstr_secname = concat (stab_secname, "str", (char *) NULL);
if (saved_secname)
{
free (saved_secname);
free (saved_strsecname);
}
saved_secname = stab_secname;
saved_strsecname = stabstr_secname;
}
s_stab_generic (what, saved_secname, saved_strsecname);
stabstr_secname = concat (stab_secname, "str", (char *) NULL);
s_stab_generic (what, stab_secname, stabstr_secname,
stab_secname_obstack_end);
}
#ifdef S_SET_DESC

2
gas/testsuite/gas/all/gas.exp
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@ -472,3 +472,5 @@ run_dump_test "org-5"
run_dump_test "org-6"
run_dump_test "fill-1"
gas_test "pr23938.s" "" "" ".xstabs"

2
gas/testsuite/gas/all/pr23938.s Normal file
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@ -0,0 +1,2 @@
.xstabs ".stab.index","main",36,0,0,0
.xstabs ".stab.foo","main",36,0,0,0