From patchwork Mon Feb 24 10:34:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 11400153 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 558D914D5 for ; Mon, 24 Feb 2020 10:34:57 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2C4C620828 for ; Mon, 24 Feb 2020 10:34:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KwYpSGHg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C4C620828 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:34432 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6B4h-0001PO-VA for patchwork-qemu-devel@patchwork.kernel.org; Mon, 24 Feb 2020 05:34:55 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:44057) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6B4A-0000O1-5t for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6B48-0007l0-V9 for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:22 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:52297 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1j6B48-0007kl-Ri for qemu-devel@nongnu.org; Mon, 24 Feb 2020 05:34:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582540460; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6DuJZhufpf0aFOVc/6GZove5MAyebHMgmt+bclbTTvM=; b=KwYpSGHgeMOi0DCyQdRfqt1232ZLa1XNc9C6TgUTlGlBZlQAS8JpMnXa+QgGPoDqhV8pdr utxm3XCmu+4Ka4s0Tkp+mC2mJhQx7r243RqSufixq11Ya40mJZHT+6LK812ODXiYc22wwP ayM1O0274Yx52nHkfwjmZImQAAmlFek= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-148-KJx8PHpxNPWNMHVN8cecqg-1; Mon, 24 Feb 2020 05:34:16 -0500 X-MC-Unique: KJx8PHpxNPWNMHVN8cecqg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A4934800D5A; Mon, 24 Feb 2020 10:34:15 +0000 (UTC) Received: from localhost (unknown [10.36.118.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9552A27081; Mon, 24 Feb 2020 10:34:12 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 1/2] qemu/queue.h: clear linked list pointers on remove Date: Mon, 24 Feb 2020 10:34:05 +0000 Message-Id: <20200224103406.1894923-2-stefanha@redhat.com> In-Reply-To: <20200224103406.1894923-1-stefanha@redhat.com> References: <20200224103406.1894923-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.61 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Do not leave stale linked list pointers around after removal. It's safer to set them to NULL so that use-after-removal results in an immediate segfault. The RCU queue removal macros are unchanged since nodes may still be traversed after removal. Suggested-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- include/qemu/queue.h | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/include/qemu/queue.h b/include/qemu/queue.h index 294db54eb1..456a5b01ee 100644 --- a/include/qemu/queue.h +++ b/include/qemu/queue.h @@ -142,6 +142,8 @@ struct { \ (elm)->field.le_next->field.le_prev = \ (elm)->field.le_prev; \ *(elm)->field.le_prev = (elm)->field.le_next; \ + (elm)->field.le_next = NULL; \ + (elm)->field.le_prev = NULL; \ } while (/*CONSTCOND*/0) /* @@ -225,12 +227,15 @@ struct { \ } while (/*CONSTCOND*/0) #define QSLIST_REMOVE_HEAD(head, field) do { \ - (head)->slh_first = (head)->slh_first->field.sle_next; \ + typeof((head)->slh_first) elm = (head)->slh_first; \ + (head)->slh_first = elm->field.sle_next; \ + elm->field.sle_next = NULL; \ } while (/*CONSTCOND*/0) #define QSLIST_REMOVE_AFTER(slistelm, field) do { \ - (slistelm)->field.sle_next = \ - QSLIST_NEXT(QSLIST_NEXT((slistelm), field), field); \ + typeof(slistelm) next = (slistelm)->field.sle_next; \ + (slistelm)->field.sle_next = next->field.sle_next; \ + next->field.sle_next = NULL; \ } while (/*CONSTCOND*/0) #define QSLIST_REMOVE(head, elm, type, field) do { \ @@ -241,6 +246,7 @@ struct { \ while (curelm->field.sle_next != (elm)) \ curelm = curelm->field.sle_next; \ curelm->field.sle_next = curelm->field.sle_next->field.sle_next; \ + (elm)->field.sle_next = NULL; \ } \ } while (/*CONSTCOND*/0) @@ -304,8 +310,10 @@ struct { \ } while (/*CONSTCOND*/0) #define QSIMPLEQ_REMOVE_HEAD(head, field) do { \ - if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL)\ + typeof((head)->sqh_first) elm = (head)->sqh_first; \ + if (((head)->sqh_first = elm->field.sqe_next) == NULL) \ (head)->sqh_last = &(head)->sqh_first; \ + elm->field.sqe_next = NULL; \ } while (/*CONSTCOND*/0) #define QSIMPLEQ_SPLIT_AFTER(head, elm, field, removed) do { \ @@ -329,6 +337,7 @@ struct { \ if ((curelm->field.sqe_next = \ curelm->field.sqe_next->field.sqe_next) == NULL) \ (head)->sqh_last = &(curelm)->field.sqe_next; \ + (elm)->field.sqe_next = NULL; \ } \ } while (/*CONSTCOND*/0) @@ -446,6 +455,8 @@ union { \ (head)->tqh_circ.tql_prev = (elm)->field.tqe_circ.tql_prev; \ (elm)->field.tqe_circ.tql_prev->tql_next = (elm)->field.tqe_next; \ (elm)->field.tqe_circ.tql_prev = NULL; \ + (elm)->field.tqe_circ.tql_next = NULL; \ + (elm)->field.tqe_next = NULL; \ } while (/*CONSTCOND*/0) /* remove @left, @right and all elements in between from @head */ From patchwork Mon Feb 24 10:34:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 11400155 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BB822930 for ; Mon, 24 Feb 2020 10:35:55 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9146020828 for ; 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Mon, 24 Feb 2020 05:34:21 -0500 X-MC-Unique: FXvQdUtIOuian3xrOq9dCQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6CAB7800D5B; Mon, 24 Feb 2020 10:34:20 +0000 (UTC) Received: from localhost (unknown [10.36.118.58]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1CA8B91851; Mon, 24 Feb 2020 10:34:16 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH 2/2] aio-posix: remove confusing QLIST_SAFE_REMOVE() Date: Mon, 24 Feb 2020 10:34:06 +0000 Message-Id: <20200224103406.1894923-3-stefanha@redhat.com> In-Reply-To: <20200224103406.1894923-1-stefanha@redhat.com> References: <20200224103406.1894923-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" QLIST_SAFE_REMOVE() is confusing here because the node must be on the list. We actually just wanted to clear the linked list pointers when removing it from the list. QLIST_REMOVE() now does this, so switch to it. Suggested-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- util/aio-posix.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/util/aio-posix.c b/util/aio-posix.c index 7e6c9835bb..026c1f5286 100644 --- a/util/aio-posix.c +++ b/util/aio-posix.c @@ -493,7 +493,7 @@ static bool aio_dispatch_ready_handlers(AioContext *ctx, AioHandler *node; while ((node = QLIST_FIRST(ready_list))) { - QLIST_SAFE_REMOVE(node, node_ready); + QLIST_REMOVE(node, node_ready); progress = aio_dispatch_handler(ctx, node) || progress; }