From patchwork Fri Jan 3 07:30:38 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 13925267 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC7001C82E2; Fri, 3 Jan 2025 07:30:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735889455; cv=none; b=XU8KJLUAJjllhGK8i506ZZaGAIHkTqAsKjXPs2tCmkxOOtSpsbvRFJZNbm3IExHSspFLjtpTFFmFlmYqgSwOv30Vx6NGAx4wzhZ8PpODMo6lsR1fN8bWEvmtDj788m9NQ2DDE7BAu4UAoXSs5lsIs+c52GfUvOHMjHxR/+9vTQE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735889455; c=relaxed/simple; bh=8d9RnOeLxBAYfLB453OSPY3ovNxvISADOh5P9Ux7SfE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=pw06yEw3p6SuOyxLPeRXlNy2bu+614BMUQKCltbkl3XRd86w3KTpwhoWMZW+6S1Or/3ff4tjVKNScj3sMWsl6fuwJCqrcoPnjbdYSF+l4eDs51pO7yKj0Wf223qXcerohw4qk6JAU5Ugu08KNRXZP2rmNSfqN4dJeDU6a8dtJlc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G1FTYZ2x; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G1FTYZ2x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7762C4CECE; Fri, 3 Jan 2025 07:30:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735889455; bh=8d9RnOeLxBAYfLB453OSPY3ovNxvISADOh5P9Ux7SfE=; h=From:To:Cc:Subject:Date:From; b=G1FTYZ2xqVXzD/lOUPB4bzpuvMR2PBLPmCoBQGI28j4YUIf7rB4dVFYZ0NyySWXF/ eli4vpBdGb7p/U5duCuiNdhnjJHHriX7lBIp/+m4VlU2k1mriouKnhHHjv9JTkiN58 U7noPwXsR2uLqqeSYBIkVhuhSwhwN6gdKqE9p54z6AnX5luT6WAzoGSl4LbqZSrB+f Q+fTuKk+/bzV6DOeVWtmcTFOoWvO3bwc0ThaWc2SN4gD8SiBfgSxMFtWJqsLWjaD14 ahfIBT94ZQVw+wRoOlNX7/FapPuqS8BVZuugdbaKs8y3WajL7kn3c+6P3bBRbu+rZP Ja3qkU7UzixOQ== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Masahiro Yamada , Andreas Gruenbacher , Andrew Morton , Sam Ravnborg Subject: [PATCH 1/6] genksyms: fix memory leak when the same symbol is added from source Date: Fri, 3 Jan 2025 16:30:38 +0900 Message-ID: <20250103073046.2609911-1-masahiroy@kernel.org> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 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 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 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 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 --- scripts/genksyms/genksyms.c | 3 +++ scripts/genksyms/parse.y | 14 ++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c index 07f9b8cfb233..8ca46f807b57 100644 --- a/scripts/genksyms/genksyms.c +++ b/scripts/genksyms/genksyms.c @@ -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; diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y index 8e9b5e69e8f0..840371d01bf4 100644 --- a/scripts/genksyms/parse.y +++ b/scripts/genksyms/parse.y @@ -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;