de5fe16817
The content of this branch was automatically imported from Fedora ELN with the following as its source: https://src.fedoraproject.org/rpms/device-mapper-multipath#2cf40b2f98808e3533e915c0a204b885d9da5e43
85 lines
2.7 KiB
Diff
85 lines
2.7 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: lixiaokeng <lixiaokeng@huawei.com>
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Date: Mon, 13 Jul 2020 13:07:40 +0200
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Subject: [PATCH] master - libmultipath: fix use after free when iscsi logs in
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When two iscsi ips log in and out alternately and the following scripts run
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at the same time,
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#!/bin/bash
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interval=5
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while true
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do
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iscsiadm -m node -p 9.41.147.171 &> /dev/null
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iscsiadm -m node -p 9.41.148.172 &> /dev/null
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iscsiadm -m session &> /dev/null
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rescan-scsi-bus.sh &> /dev/null
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multipath -v2 &> /dev/null
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multipath -ll &> /dev/null
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sleep $interval
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done
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multipathd will have a segfault after about 30 mins.
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The reason is that mpp->hwe is accessed after hwe is already freed. In
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extract_hwe_from_path func, mpp->hwe is set to pp->hwe, so they points to the
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same hwe. For some reasons, pp->mpp will be set to NULL in orphan_path func.
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Then, pp and hwe will be freed with (pp->mpp == NULL) in free_path func
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called by ev_remove_path func. However, mpp->hwe is not set to NULL while hwe
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is already freed. So, when iscsi device logs in and new path is added to mpp,
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mpp->hwe will be accessed in select_pgfailback func. Finally, use-after-free
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problem occurs.
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The procedure details given as follows,
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1.wait_dmevents thread
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wait_dmevents
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->dmevent_loop
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->update_multipath
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->__setup_multipath
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->update_multipath_strings
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-> sync_paths
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->orphan_path
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2.uevqloop thread (iscsi log out, remove path)
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uevqloop
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->uevent_dispatch
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->service_uevq
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->uev_remove_path
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->ev_remove_path //pp->mpp is NULL
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->free_path(pp)
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//pp->hew are freed but mpp->hwe is not set to NULL
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3.ev_remove_path (iscsi log in, add path)
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uevqloop
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->uevent_dispatch
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->service_uevq
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->ev_add_path
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->select_pgfailback //mpp->hwe is accessed
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Here, we will set mpp->hwe to NULL before setting pp->map to NULL in orphan_path
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func.
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Signed-off-by: Tianxiong Lu <lutianxiong@huawei.com>
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Signed-off-by: lixiaokeng <lixiaokeng@huawei.com>
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Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
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Signed-off-by: Martin Wilck <mwilck@suse.com>
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Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
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---
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libmultipath/structs_vec.c | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
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index 8137ea21..430eaad7 100644
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--- a/libmultipath/structs_vec.c
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+++ b/libmultipath/structs_vec.c
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@@ -93,6 +93,8 @@ int adopt_paths(vector pathvec, struct multipath *mpp)
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void orphan_path(struct path *pp, const char *reason)
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{
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condlog(3, "%s: orphan path, %s", pp->dev, reason);
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+ if (pp->mpp && pp->mpp->hwe == pp->hwe)
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+ pp->mpp->hwe = NULL;
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pp->mpp = NULL;
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pp->dmstate = PSTATE_UNDEF;
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pp->uid_attribute = NULL;
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--
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2.17.2
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