@@ -239,6 +239,7 @@ static struct symbol *__add_symbol(const char *name, enum symbol_type type,
"unchanged\n");
}
sym->is_declared = 1;
+ free_list(defn, NULL);
return sym;
} else if (!sym->is_declared) {
if (sym->is_override && flag_preserve) {
@@ -247,6 +248,7 @@ static struct symbol *__add_symbol(const char *name, enum symbol_type type,
print_type_name(type, name);
fprintf(stderr, " modversion change\n");
sym->is_declared = 1;
+ free_list(defn, NULL);
return sym;
} else {
status = is_unknown_symbol(sym) ?
@@ -254,6 +256,7 @@ static struct symbol *__add_symbol(const char *name, enum symbol_type type,
}
} else {
error_with_pos("redefinition of %s", name);
+ free_list(defn, NULL);
return sym;
}
break;
@@ -152,14 +152,19 @@ simple_declaration:
;
init_declarator_list_opt:
- /* empty */ { $$ = NULL; }
- | init_declarator_list
+ /* empty */ { $$ = NULL; }
+ | init_declarator_list { free_list(decl_spec, NULL); $$ = $1; }
;
init_declarator_list:
init_declarator
{ struct string_list *decl = *$1;
*$1 = NULL;
+
+ /* avoid sharing among multiple init_declarators */
+ if (decl_spec)
+ decl_spec = copy_list_range(decl_spec, NULL);
+
add_symbol(current_name,
is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
current_name = NULL;
@@ -170,6 +175,11 @@ init_declarator_list:
*$3 = NULL;
free_list(*$2, NULL);
*$2 = decl_spec;
+
+ /* avoid sharing among multiple init_declarators */
+ if (decl_spec)
+ decl_spec = copy_list_range(decl_spec, NULL);
+
add_symbol(current_name,
is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
current_name = NULL;
When a symbol that is already registered is added again, __add_symbol() returns without freeing the symbol definition, making it unreachable. The following test cases demonstrate different memory leak points. [Test Case 1] Forward declaration with exactly the same definition $ cat foo.c #include <linux/export.h> void foo(void); void foo(void) {} EXPORT_SYMBOL(foo); [Test Case 2] Forward declaration with a different definition (e.g. attribute) $ cat foo.c #include <linux/export.h> void foo(void); __attribute__((__section__(".ref.text"))) void foo(void) {} EXPORT_SYMBOL(foo); [Test Case 3] Preserving an overridden symbol (compile with KBUILD_PRESERVE=1) $ cat foo.c #include <linux/export.h> void foo(void); void foo(void) { } EXPORT_SYMBOL(foo); $ cat foo.symref override foo void foo ( int ) The memory leaks in Test Case 1 and 2 have existed since the introduction of genksyms into the kernel tree. [1] The memory leak in Test Case 3 was introduced by commit 5dae9a550a74 ("genksyms: allow to ignore symbol checksum changes"). When multiple init_declarators are reduced to an init_declarator_list, the decl_spec must be duplicated. Otherwise, the following Test Case 4 would result in a double-free bug. [Test Case 4] $ cat foo.c #include <linux/export.h> extern int foo, bar; int foo, bar; EXPORT_SYMBOL(foo); In this case, 'foo' and 'bar' share the same decl_spec, 'int'. It must be unshared before being passed to add_symbol(). [1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=46bd1da672d66ccd8a639d3c1f8a166048cca608 Fixes: 5dae9a550a74 ("genksyms: allow to ignore symbol checksum changes") Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- scripts/genksyms/genksyms.c | 3 +++ scripts/genksyms/parse.y | 14 ++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-)