cb59798846
-bugfix: fix qmp command migrate-set-parameters -some bugfixs about ARM hot-plugged CPUs -hw/core/machine:Fix the missing consideration of cluster-id -test/tcg:Fix target-specific Makefile variable path for user-mode -tests:add (riscv virt) machine mapping to testenv -Make a litte improvement in curl and hw/riscv -qemu support for loongarch -hw/pvrdma: Protect against buggy or malious guest driver -hw/audio/intel-hda:fix stream reset -dsoundaudio:fix crackling audio recordings -add notify-vm-exit support for i386 -blok-backend: prevent dangling BDS pointers across aio_poll() -net:Fix uninitialized data usage -net/eth:Don't consider ESP to be an IPv6 option header -hw/net/vmxnet3:Log guest-triggerable errors using LOG_GUEST_ERROR Signed-off-by: FeiXu <xufei30@huawei.com>
125 lines
4.1 KiB
Diff
125 lines
4.1 KiB
Diff
From 6363172843fd756c61d6a3725ad5b3a385eddc87 Mon Sep 17 00:00:00 2001
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From: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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Date: Tue, 21 Mar 2023 03:02:58 +0000
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Subject: [PATCH] block-backend: prevent dangling BDS pointers across
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aio_poll() mainline inclusion commit 1e3552dbd28359d35967b7c28dc86cde1bc29205
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category: bugfix
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---------------------------------------------------------------
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The BlockBackend root child can change when aio_poll() is invoked. This
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happens when a temporary filter node is removed upon blockjob
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completion, for example.
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Functions in block/block-backend.c must be aware of this when using a
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blk_bs() pointer across aio_poll() because the BlockDriverState refcnt
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may reach 0, resulting in a stale pointer.
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One example is scsi_device_purge_requests(), which calls blk_drain() to
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wait for in-flight requests to cancel. If the backup blockjob is active,
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then the BlockBackend root child is a temporary filter BDS owned by the
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blockjob. The blockjob can complete during bdrv_drained_begin() and the
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last reference to the BDS is released when the temporary filter node is
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removed. This results in a use-after-free when blk_drain() calls
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bdrv_drained_end(bs) on the dangling pointer.
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Explicitly hold a reference to bs across block APIs that invoke
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aio_poll().
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Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2021778
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Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2036178
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-Id: <20220111153613.25453-2-stefanha@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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---
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block/block-backend.c | 19 +++++++++++++++++--
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1 file changed, 17 insertions(+), 2 deletions(-)
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diff --git a/block/block-backend.c b/block/block-backend.c
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index 49d236b2a4..3a757fb746 100644
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--- a/block/block-backend.c
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+++ b/block/block-backend.c
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@@ -840,16 +840,22 @@ BlockBackend *blk_by_public(BlockBackendPublic *public)
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void blk_remove_bs(BlockBackend *blk)
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{
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ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
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- BlockDriverState *bs;
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BdrvChild *root;
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notifier_list_notify(&blk->remove_bs_notifiers, blk);
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if (tgm->throttle_state) {
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- bs = blk_bs(blk);
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+ BlockDriverState *bs = blk_bs(blk);
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+
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+ /*
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+ * Take a ref in case blk_bs() changes across bdrv_drained_begin(), for
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+ * example, if a temporary filter node is removed by a blockjob.
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+ */
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+ bdrv_ref(bs);
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bdrv_drained_begin(bs);
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throttle_group_detach_aio_context(tgm);
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throttle_group_attach_aio_context(tgm, qemu_get_aio_context());
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bdrv_drained_end(bs);
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+ bdrv_unref(bs);
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}
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blk_update_root_state(blk);
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@@ -1731,6 +1737,7 @@ void blk_drain(BlockBackend *blk)
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BlockDriverState *bs = blk_bs(blk);
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if (bs) {
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+ bdrv_ref(bs);
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bdrv_drained_begin(bs);
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}
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@@ -1740,6 +1747,7 @@ void blk_drain(BlockBackend *blk)
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if (bs) {
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bdrv_drained_end(bs);
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+ bdrv_unref(bs);
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}
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}
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@@ -2112,10 +2120,13 @@ static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
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int ret;
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if (bs) {
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+ bdrv_ref(bs);
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+
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if (update_root_node) {
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ret = bdrv_child_try_set_aio_context(bs, new_context, blk->root,
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errp);
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if (ret < 0) {
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+ bdrv_unref(bs);
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return ret;
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}
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}
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@@ -2125,6 +2136,8 @@ static int blk_do_set_aio_context(BlockBackend *blk, AioContext *new_context,
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throttle_group_attach_aio_context(tgm, new_context);
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bdrv_drained_end(bs);
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}
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+
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+ bdrv_unref(bs);
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}
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blk->ctx = new_context;
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@@ -2394,11 +2407,13 @@ void blk_io_limits_disable(BlockBackend *blk)
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ThrottleGroupMember *tgm = &blk->public.throttle_group_member;
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assert(tgm->throttle_state);
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if (bs) {
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+ bdrv_ref(bs);
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bdrv_drained_begin(bs);
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}
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throttle_group_unregister_tgm(tgm);
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if (bs) {
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bdrv_drained_end(bs);
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+ bdrv_unref(bs);
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}
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}
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--
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2.27.0
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