From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753764AbdBEUVb (ORCPT + 2 others); Sun, 5 Feb 2017 15:21:31 -0500 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:27626 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753083AbdBETXY (ORCPT ); Sun, 5 Feb 2017 14:23:24 -0500 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: =?latin1?q?Roger=20Pau=20Monn=E9?= , David Vrabel , Konrad Rzeszutek Wilk , "Jan Beulich" , Willy Tarreau Subject: [PATCH 3.10 036/319] xen-blkback: only read request operation from shared ring once Date: Sun, 5 Feb 2017 20:20:23 +0100 Message-Id: <1486322486-8024-7-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1486322486-8024-1-git-send-email-w@1wt.eu> References: <1486322486-8024-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=latin1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Roger Pau Monné commit 1f13d75ccb806260079e0679d55d9253e370ec8a upstream. A compiler may load a switch statement value multiple times, which could be bad when the value is in memory shared with the frontend. When converting a non-native request to a native one, ensure that src->operation is only loaded once by using READ_ONCE(). This is part of XSA155. Signed-off-by: Roger Pau Monné Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk Cc: "Jan Beulich" Signed-off-by: Willy Tarreau --- drivers/block/xen-blkback/common.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index 60103e2..6774cba 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -269,8 +269,8 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst, struct blkif_x86_32_request *src) { int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; - dst->operation = src->operation; - switch (src->operation) { + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { case BLKIF_OP_READ: case BLKIF_OP_WRITE: case BLKIF_OP_WRITE_BARRIER: @@ -305,8 +305,8 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst, struct blkif_x86_64_request *src) { int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; - dst->operation = src->operation; - switch (src->operation) { + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { case BLKIF_OP_READ: case BLKIF_OP_WRITE: case BLKIF_OP_WRITE_BARRIER: -- 2.8.0.rc2.1.gbe9624a From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: =?latin1?q?Roger=20Pau=20Monn=E9?= , David Vrabel , Konrad Rzeszutek Wilk , "Jan Beulich" , Willy Tarreau Subject: [PATCH 3.10 036/319] xen-blkback: only read request operation from shared ring once Date: Sun, 5 Feb 2017 20:20:23 +0100 Message-Id: <1486322486-8024-7-git-send-email-w@1wt.eu> In-Reply-To: <1486322486-8024-1-git-send-email-w@1wt.eu> References: <1486322486-8024-1-git-send-email-w@1wt.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=latin1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: From: Roger Pau Monn� commit 1f13d75ccb806260079e0679d55d9253e370ec8a upstream. A compiler may load a switch statement value multiple times, which could be bad when the value is in memory shared with the frontend. When converting a non-native request to a native one, ensure that src->operation is only loaded once by using READ_ONCE(). This is part of XSA155. Signed-off-by: Roger Pau Monn� Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk Cc: "Jan Beulich" Signed-off-by: Willy Tarreau --- drivers/block/xen-blkback/common.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h index 60103e2..6774cba 100644 --- a/drivers/block/xen-blkback/common.h +++ b/drivers/block/xen-blkback/common.h @@ -269,8 +269,8 @@ static inline void blkif_get_x86_32_req(struct blkif_request *dst, struct blkif_x86_32_request *src) { int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; - dst->operation = src->operation; - switch (src->operation) { + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { case BLKIF_OP_READ: case BLKIF_OP_WRITE: case BLKIF_OP_WRITE_BARRIER: @@ -305,8 +305,8 @@ static inline void blkif_get_x86_64_req(struct blkif_request *dst, struct blkif_x86_64_request *src) { int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST; - dst->operation = src->operation; - switch (src->operation) { + dst->operation = READ_ONCE(src->operation); + switch (dst->operation) { case BLKIF_OP_READ: case BLKIF_OP_WRITE: case BLKIF_OP_WRITE_BARRIER: -- 2.8.0.rc2.1.gbe9624a