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From d8f974ead4b4c1f549441e7aac96262cf2b754ee Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Mon, 17 Mar 2014 22:45:29 +0100
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Subject: [PATCH 4/6] qcow2: Check bs->drv in copy_sectors()
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1395096331-12610-2-git-send-email-mreitz@redhat.com>
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Patchwork-id: 58119
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 1/3] qcow2: Check bs->drv in copy_sectors()
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Bugzilla: 1048575
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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BZ: 1048575
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Before dereferencing bs->drv for a call to its member bdrv_co_readv(),
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copy_sectors() should check whether that pointer is indeed valid, since
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it may have been set to NULL by e.g. a concurrent write triggering the
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corruption prevention mechanism.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit dba2855572c746836ad90ce9154403b5929d996b)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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block/qcow2-cluster.c | 4 ++++
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1 file changed, 4 insertions(+)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/qcow2-cluster.c | 4 ++++
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1 files changed, 4 insertions(+), 0 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index 862df0f..87c13ce 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -370,6 +370,10 @@ static int coroutine_fn copy_sectors(BlockDriverState *bs,
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BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
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+ if (!bs->drv) {
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+ return -ENOMEDIUM;
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+ }
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+
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/* Call .bdrv_co_readv() directly instead of using the public block-layer
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* interface. This avoids double I/O throttling and request tracking,
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* which can lead to deadlock when block layer copy-on-read is enabled.
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--
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1.7.1
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