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From 24f8fe9543b18cc484fc43ac1bf5bd7780656fbd Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Fri, 14 Sep 2018 10:55:35 +0200
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Subject: [PATCH 44/49] mirror: Fix potential use-after-free in active commit
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <20180914105540.18077-38-kwolf@redhat.com>
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Patchwork-id: 82188
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O-Subject: [RHV-7.6 qemu-kvm-rhev PATCH 37/42] mirror: Fix potential use-after-free in active commit
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Bugzilla: 1601212
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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When starting an active commit job, other callbacks can run before
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mirror_start_job() calls bdrv_ref() where needed and cause the nodes to
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go away. Add another pair of bdrv_ref/unref() around it to protect
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against this case.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/mirror.c | 11 +++++++++++
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1 file changed, 11 insertions(+)
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diff --git a/block/mirror.c b/block/mirror.c
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index 4b27f71..8658873 100644
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--- a/block/mirror.c
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+++ b/block/mirror.c
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@@ -1335,7 +1335,14 @@ void commit_active_start(const char *job_id, BlockDriverState *bs,
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orig_base_flags = bdrv_get_flags(base);
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+ /* bdrv_reopen() drains, which might make the BDSes go away before a
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+ * reference is taken in mirror_start_job(). */
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+ bdrv_ref(bs);
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+ bdrv_ref(base);
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+
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if (bdrv_reopen(base, bs->open_flags, errp)) {
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+ bdrv_unref(bs);
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+ bdrv_unref(base);
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return;
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}
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@@ -1344,6 +1351,10 @@ void commit_active_start(const char *job_id, BlockDriverState *bs,
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on_error, on_error, true, cb, opaque,
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&commit_active_job_driver, false, base, auto_complete,
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filter_node_name, false, &local_err);
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+
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+ bdrv_unref(bs);
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+ bdrv_unref(base);
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+
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if (local_err) {
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error_propagate(errp, local_err);
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goto error_restore_flags;
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--
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1.8.3.1
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