From mboxrd@z Thu Jan 1 00:00:00 1970 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 8D15025E836; Tue, 11 Mar 2025 15:05:41 +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=1741705541; cv=none; b=hcH/DC8cjpCLMIfhBqFF4yakVwVTs1jIOFj7y4ewMWftDlhDmoxnRTq/rZxprhtFD+EjEfBLJlEj1phm30OPfgstx/HtYjvtYuZcJ6CZHtLtMmrG4al/4w3GokHEGu9pEXzlMMFyUj1B3UmWqmYL4Rn60K/SIfPPoZ0KP3QYV7A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741705541; c=relaxed/simple; bh=Uvrr5a4fzGB7RDIJ+pSYQpKAgP5x/uEbF7/uAESJvk0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ElyQ8SB32DwPWE+qKBSS5lMnI8LOpanT1opNtNIEl/jnFqUcMyi/6RySL4XcwFlLeiGJEFFLjacsREYryJdnWhEkYY366NVFUn95WO8Prgnap6nVwAy1dfVXq75Y4tEae30U1i1Tqa5VLSwN/XY3R54Pcb+6zA6pljuWbOGS8ho= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Y0iPndUC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Y0iPndUC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15810C4CEEC; Tue, 11 Mar 2025 15:05:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1741705541; bh=Uvrr5a4fzGB7RDIJ+pSYQpKAgP5x/uEbF7/uAESJvk0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y0iPndUCVFL2/WfVjpewqhoWtQBrkToTycUlVbXGC1+ajEnqD9b93+TLjUe8WZUq6 YNpHsUY4/CuN5FKBr2cSXG2NYq4kFrXL7e/tApYOovJ6mtwAf9jm0727IUtdioFee+ Px09Amr6Ebf0gbvoVk0Y3i0nNV3QAzZNzRJLwLkM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masahiro Yamada , Sasha Levin Subject: [PATCH 5.4 071/328] genksyms: fix memory leak when the same symbol is added from source Date: Tue, 11 Mar 2025 15:57:21 +0100 Message-ID: <20250311145717.714735283@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250311145714.865727435@linuxfoundation.org> References: <20250311145714.865727435@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Masahiro Yamada [ Upstream commit 45c9c4101d3d2fdfa00852274bbebba65fcc3cf2 ] 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 Signed-off-by: Sasha Levin --- 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 23eff234184f3..d74bad87ef1a7 100644 --- a/scripts/genksyms/genksyms.c +++ b/scripts/genksyms/genksyms.c @@ -241,6 +241,7 @@ 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) { @@ -249,6 +250,7 @@ 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) ? @@ -256,6 +258,7 @@ 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 e22b42245bcc2..7df3fe290d535 100644 --- a/scripts/genksyms/parse.y +++ b/scripts/genksyms/parse.y @@ -149,14 +149,19 @@ 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; @@ -167,6 +172,11 @@ 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; -- 2.39.5