5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Masahiro Yamada masahiroy@kernel.org
[ Upstream commit be2fa44b5180a1f021efb40c55fdf63c249c3209 ]
When a symbol that is already registered is read again from *.symref file, __add_symbol() removes the previous one from the hash table without freeing it.
[Test Case]
$ cat foo.c #include <linux/export.h> void foo(void); void foo(void) {} EXPORT_SYMBOL(foo);
$ cat foo.symref foo void foo ( void ) foo void foo ( void )
When a symbol is removed from the hash table, it must be freed along with its ->name and ->defn members. However, sym->name cannot be freed because it is sometimes shared with node->string, but not always. If sym->name and node->string share the same memory, free(sym->name) could lead to a double-free bug.
To resolve this issue, always assign a strdup'ed string to sym->name.
Fixes: 64e6c1e12372 ("genksyms: track symbol checksum changes") Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/genksyms/genksyms.c | 8 ++++++-- scripts/genksyms/genksyms.h | 2 +- scripts/genksyms/parse.y | 4 ++-- 3 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c index d74bad87ef1a7..a87fafbbec268 100644 --- a/scripts/genksyms/genksyms.c +++ b/scripts/genksyms/genksyms.c @@ -274,11 +274,15 @@ static struct symbol *__add_symbol(const char *name, enum symbol_type type, break; } } + + free_list(sym->defn, NULL); + free(sym->name); + free(sym); --nsyms; }
sym = xmalloc(sizeof(*sym)); - sym->name = name; + sym->name = xstrdup(name); sym->type = type; sym->defn = defn; sym->expansion_trail = NULL; @@ -485,7 +489,7 @@ static void read_reference(FILE *f) defn = def; def = read_node(f); } - subsym = add_reference_symbol(xstrdup(sym->string), sym->tag, + subsym = add_reference_symbol(sym->string, sym->tag, defn, is_extern); subsym->is_override = is_override; free_node(sym); diff --git a/scripts/genksyms/genksyms.h b/scripts/genksyms/genksyms.h index 2bcdb9bebab40..4ead4e0adb821 100644 --- a/scripts/genksyms/genksyms.h +++ b/scripts/genksyms/genksyms.h @@ -32,7 +32,7 @@ struct string_list {
struct symbol { struct symbol *hash_next; - const char *name; + char *name; enum symbol_type type; struct string_list *defn; struct symbol *expansion_trail; diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y index 7df3fe290d535..84813ce54a2dd 100644 --- a/scripts/genksyms/parse.y +++ b/scripts/genksyms/parse.y @@ -479,12 +479,12 @@ enumerator_list: enumerator: IDENT { - const char *name = strdup((*$1)->string); + const char *name = (*$1)->string; add_symbol(name, SYM_ENUM_CONST, NULL, 0); } | IDENT '=' EXPRESSION_PHRASE { - const char *name = strdup((*$1)->string); + const char *name = (*$1)->string; struct string_list *expr = copy_list_range(*$3, *$2); add_symbol(name, SYM_ENUM_CONST, expr, 0); }