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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF673C433EF for ; Tue, 24 May 2022 16:00:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7E9EA8D0005; Tue, 24 May 2022 12:00:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 799948D0001; Tue, 24 May 2022 12:00:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 687018D0005; Tue, 24 May 2022 12:00:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 5AD2A8D0001 for ; Tue, 24 May 2022 12:00:28 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay12.hostedemail.com (Postfix) with ESMTP id 1C08D120263 for ; Tue, 24 May 2022 16:00:28 +0000 (UTC) X-FDA: 79501098936.27.9655C2C Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf21.hostedemail.com (Postfix) with ESMTP id 98C461C00DD for ; Tue, 24 May 2022 16:00:14 +0000 (UTC) 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 9AF9E615B2; Tue, 24 May 2022 16:00:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79D67C3411D; Tue, 24 May 2022 16:00:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653408019; bh=003EFPVAWAtkcipXIjXUvRz6XdQ5O2kKi9sJjDH1Xkc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IC+ovL0nDg3sYrxw7fREcYuemoky9I3xbWoB7zboOmVgOipbgeqIs5oF4NcW7dzBv qOkNqypAhhInxkSNuUZ7Tp/WKH/5WICJSMfEzhT52UsyM7kcXzQdaGXqOTTkr269Ua OwAyZNzAGaPrq/u3amWpZI1Ew2bmnFI6e8Lcz4qKyO4m1g6iC4FNcE1m2x8S0tu6a2 3W30AtZtTvI5jdyQaWdh8cmvPkYbg8JRR7xBM8RtvAfaBJN0Z8QdNz3MgBHCuzG22v 0iW7OQgo0fO+p1EPI7viuHFJnsShqh8qeldiGTv3Xnpnh/hz14woggZhTo8gCfRln1 3DAoLezWf8GxQ== 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 5.15 05/10] percpu_ref_init(): clean ->percpu_count_ref on failure Date: Tue, 24 May 2022 12:00:02 -0400 Message-Id: <20220524160009.826957-5-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220524160009.826957-1-sashal@kernel.org> References: <20220524160009.826957-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 98C461C00DD X-Stat-Signature: 5wtdwfdbdn3bm13wtnyiw6phuz4tnt49 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=IC+ovL0n; spf=pass (imf21.hostedemail.com: domain of sashal@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sashal@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspam-User: X-HE-Tag: 1653408014-62091 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 af9302141bcf..e5c5315da274 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -76,6 +76,7 @@ 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