FreeChainXenon/binutils-gdb
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Use unique_ptr to destroy per-bfd object

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In some cases, the objfile owns the per-bfd object.  This is yet
another object that can sometimes be destroyed before the registry is
destroyed, possibly reslting in a use-after-free.  Also, I noticed
that the condition for deleting the object is not the same as the
condition used to create it -- so it could possibly result in a memory
leak in some situations.  This patch fixes the problem by introducing
a new unique_ptr that holds this object when necessary.
This commit is contained in:
Tom Tromey 2022-08-02 12:01:01 -06:00
parent 075e4d6d95
commit 88c4cce8d2
2 changed files with 14 additions and 17 deletions
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22
gdb/objfiles.c
View file

@ -117,9 +117,10 @@ objfile_per_bfd_storage::~objfile_per_bfd_storage ()
NULL, and it already has a per-BFD storage object, use that. NULL, and it already has a per-BFD storage object, use that.
Otherwise, allocate a new per-BFD storage object. */ Otherwise, allocate a new per-BFD storage object. */
static struct objfile_per_bfd_storage * void
get_objfile_bfd_data (bfd *abfd) set_objfile_per_bfd (struct objfile *objfile)
{ {
bfd *abfd = objfile->obfd.get ();
struct objfile_per_bfd_storage *storage = NULL; struct objfile_per_bfd_storage *storage = NULL;
if (abfd != NULL) if (abfd != NULL)
@ -133,21 +134,15 @@ get_objfile_bfd_data (bfd *abfd)
enough that this seems reasonable. */ enough that this seems reasonable. */
if (abfd != NULL && !gdb_bfd_requires_relocations (abfd)) if (abfd != NULL && !gdb_bfd_requires_relocations (abfd))
objfiles_bfd_data.set (abfd, storage); objfiles_bfd_data.set (abfd, storage);
else
objfile->per_bfd_storage.reset (storage);
/* Look up the gdbarch associated with the BFD. */ /* Look up the gdbarch associated with the BFD. */
if (abfd != NULL) if (abfd != NULL)
storage->gdbarch = gdbarch_from_bfd (abfd); storage->gdbarch = gdbarch_from_bfd (abfd);
} }
return storage; objfile->per_bfd = storage;
}
/* See objfiles.h. */
void
set_objfile_per_bfd (struct objfile *objfile)
{
objfile->per_bfd = get_objfile_bfd_data (objfile->obfd.get ());
} }
/* Set the objfile's per-BFD notion of the "main" name and /* Set the objfile's per-BFD notion of the "main" name and
@ -353,7 +348,7 @@ objfile::objfile (gdb_bfd_ref_ptr bfd_, const char *name, objfile_flags flags_)
build_objfile_section_table (this); build_objfile_section_table (this);
} }
per_bfd = get_objfile_bfd_data (obfd.get ()); set_objfile_per_bfd (this);
} }
/* If there is a valid and known entry point, function fills *ENTRY_P with it /* If there is a valid and known entry point, function fills *ENTRY_P with it
@ -555,9 +550,6 @@ objfile::~objfile ()
if (sf != NULL) if (sf != NULL)
(*sf->sym_finish) (this); (*sf->sym_finish) (this);
if (obfd == nullptr)
delete per_bfd;
/* Before the symbol table code was redone to make it easier to /* Before the symbol table code was redone to make it easier to
selectively load and remove information particular to a specific selectively load and remove information particular to a specific
linkage unit, gdb used to do these things whenever the monolithic linkage unit, gdb used to do these things whenever the monolithic

9
gdb/objfiles.h
View file

@ -653,11 +653,16 @@ public:
gdb_bfd_ref_ptr obfd; gdb_bfd_ref_ptr obfd;
/* The per-BFD data. Note that this is treated specially if OBFD /* The per-BFD data. */
is NULL. */
struct objfile_per_bfd_storage *per_bfd = nullptr; struct objfile_per_bfd_storage *per_bfd = nullptr;
/* In some cases, the per_bfd object is owned by this objfile and
not by the BFD itself. In this situation, this holds the owning
pointer. */
std::unique_ptr<objfile_per_bfd_storage> per_bfd_storage;
/* The modification timestamp of the object file, as of the last time /* The modification timestamp of the object file, as of the last time
we read its symbols. */ we read its symbols. */