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 A9BADC32772 for ; Tue, 23 Aug 2022 09:47:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243551AbiHWJrw (ORCPT ); Tue, 23 Aug 2022 05:47:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351867AbiHWJpg (ORCPT ); Tue, 23 Aug 2022 05:45:36 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69CFD208; Tue, 23 Aug 2022 01:43:18 -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 sin.source.kernel.org (Postfix) with ESMTPS id 0178BCE1B50; Tue, 23 Aug 2022 08:42:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FF05C433C1; Tue, 23 Aug 2022 08:42:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661244152; bh=gRXOJdIGssNxS+kxPIDu1FjF/pzKNtVhwUjsxe9M6fk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yDb5JIx2zqETTGlPmFQeUY6W4VMqsjo5rLSZEZc14OQXbm05YZXzLicCK8TsM3R23 cb1XSE91wySBHMzb5/p3wkRKjDxmq9Rstc96lD1Yyb/pQjeFM7LjIzAXXQUKCneiie Q/kpATAz02klIJzxIFpQIR4CO9gKLtfGdRAZd430= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hou Tao , Yonghong Song , Alexei Starovoitov Subject: [PATCH 5.15 044/244] bpf: Acquire map uref in .init_seq_private for array map iterator Date: Tue, 23 Aug 2022 10:23:23 +0200 Message-Id: <20220823080100.536819994@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080059.091088642@linuxfoundation.org> References: <20220823080059.091088642@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hou Tao commit f76fa6b338055054f80c72b29c97fb95c1becadc upstream. bpf_iter_attach_map() acquires a map uref, and the uref may be released before or in the middle of iterating map elements. For example, the uref could be released in bpf_iter_detach_map() as part of bpf_link_release(), or could be released in bpf_map_put_with_uref() as part of bpf_map_release(). Alternative fix is acquiring an extra bpf_link reference just like a pinned map iterator does, but it introduces unnecessary dependency on bpf_link instead of bpf_map. So choose another fix: acquiring an extra map uref in .init_seq_private for array map iterator. Fixes: d3cc2ab546ad ("bpf: Implement bpf iterator for array maps") Signed-off-by: Hou Tao Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20220810080538.1845898-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/arraymap.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -620,6 +620,11 @@ static int bpf_iter_init_array_map(void seq_info->percpu_value_buf = value_buf; } + /* bpf_iter_attach_map() acquires a map uref, and the uref may be + * released before or in the middle of iterating map elements, so + * acquire an extra map uref for iterator. + */ + bpf_map_inc_with_uref(map); seq_info->map = map; return 0; } @@ -628,6 +633,7 @@ static void bpf_iter_fini_array_map(void { struct bpf_iter_seq_array_map_info *seq_info = priv_data; + bpf_map_put_with_uref(seq_info->map); kfree(seq_info->percpu_value_buf); }