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[Darwin] Fix cleanup leak in machoread.c:macho_symfile_read 

This patch fixes a cleanup leak in macho_symfile_read (symbol_table):

          symbol_table = (asymbol **) xmalloc (storage_needed);
          make_cleanup (xfree, symbol_table);

Unfortunately, fixing the leak alone triggers a crash which occurs
while loading the symbols from an executable:

    % gdb
    (gdb) file g_exe
    [SIGSEGV]

The crash is caused by the fact that performing the cleanup
right after the call to macho_symtab_read, as currently done,
is too early.

Indeed, references to this symbol_table get saved in the oso_vector
global during the call to macho_symtab_read via calls to
macho_register_oso, and those references then get accessed
later on, when processing all the OSOs that got pushed (see
call to macho_symfile_read_all_oso).

This patch prevents this by using one single cleanup queue for
the entire function, rather than having additional separate
cleanup queues (Eg: for the handling of the minimal symbols),
thus preventing the premature free'ing of the minimal_symbols
array.

Secondly, this patch takes this opportunity for avoiding the use
of the oso_vector global, thus making it simpler to track its
lifetime.

gdb/ChangeLog:

        * machoread.c (oso_vector): Delete this global.
        (macho_register_oso): Add new parameter "oso_vector_ptr".
        Use it instead of the "oso_vector" global.
        (macho_symtab_read, macho_symfile_read_all_oso): Likewise.
        (macho_symfile_read): Use a local oso_vector, to be free'ed
        at the end of this function, in place of the old "oso_vector"
        global.  Update various function calls accordingly.  Use one
        single cleanup chain for the entire function.
This commit is contained in:
Joel Brobecker 2013-06-18 23:35:37 +00:00
parent 59b0c7c17a
commit 8b89a20adb
2 changed files with 35 additions and 26 deletions
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11
gdb/ChangeLog
View File

@ -1,3 +1,14 @@
2013-06-18 Joel Brobecker <brobecker@adacore.com>
* machoread.c (oso_vector): Delete this global.
(macho_register_oso): Add new parameter "oso_vector_ptr".
Use it instead of the "oso_vector" global.
(macho_symtab_read, macho_symfile_read_all_oso): Likewise.
(macho_symfile_read): Use a local oso_vector, to be free'ed
at the end of this function, in place of the old "oso_vector"
global. Update various function calls accordingly. Use one
single cleanup chain for the entire function.
2013-06-18 Joel Brobecker <brobecker@adacore.com>
* dwarf2read.c (dwarf2_per_objfile): Replace uses of

50
gdb/machoread.c
View File

@ -64,10 +64,8 @@ typedef struct oso_el
}
oso_el;
/* Vector of object files to be read after the executable. This is one
global variable but it's life-time is the one of macho_symfile_read. */
/* Vector of object files to be read after the executable. */
DEF_VEC_O (oso_el);
static VEC (oso_el) *oso_vector;
static void
macho_new_init (struct objfile *objfile)
@ -83,7 +81,8 @@ macho_symfile_init (struct objfile *objfile)
/* Add a new OSO to the vector of OSO to load. */
static void
macho_register_oso (struct objfile *objfile,
macho_register_oso (VEC (oso_el) **oso_vector_ptr,
struct objfile *objfile,
asymbol **oso_sym, asymbol **end_sym,
unsigned int nbr_syms)
{
@ -94,7 +93,7 @@ macho_register_oso (struct objfile *objfile,
el.oso_sym = oso_sym;
el.end_sym = end_sym;
el.nbr_syms = nbr_syms;
VEC_safe_push (oso_el, oso_vector, &el);
VEC_safe_push (oso_el, *oso_vector_ptr, &el);
}
/* Add symbol SYM to the minimal symbol table of OBJFILE. */
@ -175,7 +174,8 @@ macho_symtab_add_minsym (struct objfile *objfile, const asymbol *sym)
static void
macho_symtab_read (struct objfile *objfile,
long number_of_symbols, asymbol **symbol_table)
long number_of_symbols, asymbol **symbol_table,
VEC (oso_el) **oso_vector_ptr)
{
long i;
const asymbol *dir_so = NULL;
@ -299,7 +299,8 @@ macho_symtab_read (struct objfile *objfile,
{
/* End of file. */
if (state == S_DWARF_FILE)
macho_register_oso (objfile, oso_file, symbol_table + i,
macho_register_oso (oso_vector_ptr, objfile,
oso_file, symbol_table + i,
nbr_syms);
state = S_NO_SO;
}
@ -642,19 +643,20 @@ macho_add_oso_symfile (oso_el *oso, bfd *abfd,
do_cleanups (cleanup);
}
/* Read symbols from the vector of oso files. */
/* Read symbols from the vector of oso files.
Note that this function sorts OSO_VECTOR_PTR. */
static void
macho_symfile_read_all_oso (struct objfile *main_objfile, int symfile_flags)
macho_symfile_read_all_oso (VEC (oso_el) **oso_vector_ptr,
struct objfile *main_objfile,
int symfile_flags)
{
int ix;
VEC (oso_el) *vec;
VEC (oso_el) *vec = *oso_vector_ptr;
oso_el *oso;
struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
vec = oso_vector;
oso_vector = NULL;
/* Sort oso by name so that files from libraries are gathered. */
qsort (VEC_address (oso_el, vec), VEC_length (oso_el, vec),
sizeof (oso_el), oso_el_compare_name);
@ -773,7 +775,6 @@ macho_symfile_read_all_oso (struct objfile *main_objfile, int symfile_flags)
}
}
VEC_free (oso_el, vec);
do_cleanups (cleanup);
}
@ -850,6 +851,8 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
CORE_ADDR offset;
long storage_needed;
bfd *dsym_bfd;
VEC (oso_el) *oso_vector = NULL;
struct cleanup *old_chain = make_cleanup (VEC_cleanup (oso_el), &oso_vector);
/* Get symbols from the symbol table only if the file is an executable.
The symbol table of object files is not relocated and is expected to
@ -867,13 +870,12 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
{
asymbol **symbol_table;
long symcount;
struct cleanup *back_to;
symbol_table = (asymbol **) xmalloc (storage_needed);
make_cleanup (xfree, symbol_table);
init_minimal_symbol_collection ();
back_to = make_cleanup_discard_minimal_symbols ();
make_cleanup_discard_minimal_symbols ();
symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table);
@ -882,10 +884,9 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
bfd_get_filename (objfile->obfd),
bfd_errmsg (bfd_get_error ()));
macho_symtab_read (objfile, symcount, symbol_table);
macho_symtab_read (objfile, symcount, symbol_table, &oso_vector);
install_minimal_symbols (objfile);
do_cleanups (back_to);
}
/* Try to read .eh_frame / .debug_frame. */
@ -901,15 +902,10 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
int ix;
oso_el *oso;
struct bfd_section *asect, *dsect;
struct cleanup *cleanup;
if (mach_o_debug_level > 0)
printf_unfiltered (_("dsym file found\n"));
/* Remove oso. They won't be used. */
VEC_free (oso_el, oso_vector);
oso_vector = NULL;
/* Set dsym section size. */
for (asect = objfile->obfd->sections, dsect = dsym_bfd->sections;
asect && dsect;
@ -922,11 +918,11 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
}
/* Add the dsym file as a separate file. */
cleanup = make_cleanup_bfd_unref (dsym_bfd);
make_cleanup_bfd_unref (dsym_bfd);
symbol_file_add_separate (dsym_bfd, symfile_flags, objfile);
do_cleanups (cleanup);
/* Don't try to read dwarf2 from main file or shared libraries. */
do_cleanups (old_chain);
return;
}
}
@ -939,7 +935,9 @@ macho_symfile_read (struct objfile *objfile, int symfile_flags)
/* Then the oso. */
if (oso_vector != NULL)
macho_symfile_read_all_oso (objfile, symfile_flags);
macho_symfile_read_all_oso (&oso_vector, objfile, symfile_flags);
do_cleanups (old_chain);
}
static bfd_byte *