From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23B7EC433F5 for ; Tue, 24 May 2022 16:02:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239337AbiEXQCb (ORCPT ); Tue, 24 May 2022 12:02:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236311AbiEXQBg (ORCPT ); Tue, 24 May 2022 12:01:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F04E89D052; Tue, 24 May 2022 09:00:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 822ED61755; Tue, 24 May 2022 16:00:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8F06C34116; Tue, 24 May 2022 16:00:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653408043; bh=dpH0iACmdZliwu7JPRo+bUchXXFIwcB3x+lHvB7xBxI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Fh50cMdnCmdoOXsUFOGvMISx/g4v82vvuopO8vxhsesr0zbJey4GTd/NJroB649D/ 3UgbBgy+xdkAclFJloOMzMwxflg7jU2TnH2WdR1HBp3NSCDxVpowSn4BggPemhS089 g6Cdt7rXaz5QYQDKOvgbm1o/C1a2p/+v/U1Z36gomoT/8MQsfNSOzsyuqUHwsVr/bf csrw6VW0ALXhoTjEPzokX23KkuaCl47yvFld+afUFttmAQ5EHAdC0XCwFXsH0QiZoE h0CZL3UU84TZGBCCZ77FV6ubS4geu2HUeOoZlNu+cgvDcOdjgcT9CWNWkK9j13Uf9U QFS+qyhJzL8GA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Al Viro , syzbot+5b1e53987f858500ec00@syzkaller.appspotmail.com, Sasha Levin , dennis@kernel.org, tj@kernel.org, cl@linux.com, linux-mm@kvack.org Subject: [PATCH AUTOSEL 5.10 3/8] percpu_ref_init(): clean ->percpu_count_ref on failure Date: Tue, 24 May 2022 12:00:30 -0400 Message-Id: <20220524160035.827109-3-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220524160035.827109-1-sashal@kernel.org> References: <20220524160035.827109-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro [ Upstream commit a91714312eb16f9ecd1f7f8b3efe1380075f28d4 ] That way percpu_ref_exit() is safe after failing percpu_ref_init(). At least one user (cgroup_create()) had a double-free that way; there might be other similar bugs. Easier to fix in percpu_ref_init(), rather than playing whack-a-mole in sloppy users... Usual symptoms look like a messed refcounting in one of subsystems that use percpu allocations (might be percpu-refcount, might be something else). Having refcounts for two different objects share memory is Not Nice(tm)... Reported-by: syzbot+5b1e53987f858500ec00@syzkaller.appspotmail.com Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- lib/percpu-refcount.c | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index e59eda07305e..493093b97093 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -75,6 +75,7 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release, data = kzalloc(sizeof(*ref->data), gfp); if (!data) { free_percpu((void __percpu *)ref->percpu_count_ptr); + ref->percpu_count_ptr = 0; return -ENOMEM; } -- 2.35.1