fix use after free in select_pgfailback

0022-master-libmultipath-fix-use-after-free-when-iscsi-lo.patch

@@ -0,0 +1,84 @@
+From 7aa405ce7decd3609bcb76fa72a0ebe17ef3a635 Mon Sep 17 00:00:00 2001
+From: lixiaokeng <lixiaokeng@huawei.com>
+Date: Mon, 13 Jul 2020 13:07:40 +0200
+Subject: [PATCH 1/4] master - libmultipath: fix use after free when iscsi logs
+ in
+
+When two iscsi ips log in and out alternately and  the following scripts run
+at the same time,
+
+#!/bin/bash
+interval=5
+while true
+do
+        iscsiadm -m node -p 9.41.147.171 &> /dev/null
+        iscsiadm -m node -p 9.41.148.172 &> /dev/null
+        iscsiadm -m session &> /dev/null
+        rescan-scsi-bus.sh &> /dev/null
+        multipath -v2 &> /dev/null
+        multipath -ll &> /dev/null
+        sleep $interval
+done
+
+multipathd will have a segfault after about 30 mins.
+
+The reason is that mpp->hwe is accessed after hwe is already freed. In
+extract_hwe_from_path func, mpp->hwe is set to pp->hwe, so they points to the
+same hwe. For some reasons, pp->mpp will be set to NULL in orphan_path func.
+Then, pp and hwe will be freed with (pp->mpp == NULL) in free_path func
+called by ev_remove_path func. However, mpp->hwe is not set to NULL while hwe
+is already freed. So, when iscsi device logs in and new path is added to mpp,
+mpp->hwe will be accessed in select_pgfailback func. Finally, use-after-free
+problem occurs.
+
+The procedure details given as follows,
+1.wait_dmevents thread
+wait_dmevents
+	->dmevent_loop
+		->update_multipath
+			->__setup_multipath
+				->update_multipath_strings
+					 -> sync_paths
+						->orphan_path
+2.uevqloop thread  (iscsi log out, remove path)
+uevqloop
+->uevent_dispatch
+	->service_uevq
+		->uev_remove_path
+			->ev_remove_path  //pp->mpp is NULL
+				->free_path(pp)
+			//pp->hew are freed but mpp->hwe is not set to NULL
+3.ev_remove_path  (iscsi log in, add path)
+uevqloop
+->uevent_dispatch
+	->service_uevq
+		->ev_add_path
+			->select_pgfailback //mpp->hwe is accessed
+
+Here, we will set mpp->hwe to NULL before setting pp->map to NULL in orphan_path
+func.
+
+Signed-off-by: Tianxiong Lu <lutianxiong@huawei.com>
+Signed-off-by: lixiaokeng <lixiaokeng@huawei.com>
+Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
+Signed-off-by: Martin Wilck <mwilck@suse.com>
+---
+ libmultipath/structs_vec.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
+index 8137ea2..430eaad 100644
+--- a/libmultipath/structs_vec.c
++++ b/libmultipath/structs_vec.c
+@@ -93,6 +93,8 @@ int adopt_paths(vector pathvec, struct multipath *mpp)
+ void orphan_path(struct path *pp, const char *reason)
+ {
+ 	condlog(3, "%s: orphan path, %s", pp->dev, reason);
++	if (pp->mpp && pp->mpp->hwe == pp->hwe)
++		pp->mpp->hwe = NULL;
+ 	pp->mpp = NULL;
+ 	pp->dmstate = PSTATE_UNDEF;
+ 	pp->uid_attribute = NULL;
+-- 
+1.8.3.1
+

0023-libmultipath-warn-if-freeing-path-that-holds-mpp-hwe.patch

@@ -0,0 +1,32 @@
+From c44d769bbca83b7dfe643712cc783db852a41b87 Mon Sep 17 00:00:00 2001
+From: Martin Wilck <mwilck@suse.com>
+Date: Mon, 13 Jul 2020 13:07:41 +0200
+Subject: [PATCH 2/4] libmultipath: warn if freeing path that holds mpp->hwe
+
+This just adds an error message to the previous patch.
+
+Signed-off-by: Martin Wilck <mwilck@suse.com>
+---
+ libmultipath/structs_vec.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
+index 430eaad..cde4dbe 100644
+--- a/libmultipath/structs_vec.c
++++ b/libmultipath/structs_vec.c
+@@ -93,8 +93,11 @@ int adopt_paths(vector pathvec, struct multipath *mpp)
+ void orphan_path(struct path *pp, const char *reason)
+ {
+ 	condlog(3, "%s: orphan path, %s", pp->dev, reason);
+-	if (pp->mpp && pp->mpp->hwe == pp->hwe)
++	if (pp->mpp && pp->hwe && pp->mpp->hwe == pp->hwe) {
++		condlog(0, "BUG: orphaning path %s that holds hwe of %s",
++			pp->dev, pp->mpp->alias);
+ 		pp->mpp->hwe = NULL;
++	}
+ 	pp->mpp = NULL;
+ 	pp->dmstate = PSTATE_UNDEF;
+ 	pp->uid_attribute = NULL;
+-- 
+1.8.3.1
+

0024-libmultipath-warn-about-NULL-value-of-mpp-hwe.patch

@@ -0,0 +1,32 @@
+From 1b21582e297d449918ea29bec2b3a0b7ba8fa84c Mon Sep 17 00:00:00 2001
+From: Martin Wilck <mwilck@suse.com>
+Date: Mon, 13 Jul 2020 13:07:42 +0200
+Subject: [PATCH 3/4] libmultipath: warn about NULL value of mpp->hwe
+
+mpp->hwe is only accessed in propsel.c. It may become unset if
+all paths of the mpp have been deleted. Access to mpp->hwe in this
+case should be avoided.
+
+Signed-off-by: Martin Wilck <mwilck@suse.com>
+---
+ libmultipath/propsel.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
+index d362beb..6822827 100644
+--- a/libmultipath/propsel.c
++++ b/libmultipath/propsel.c
+@@ -65,7 +65,9 @@ do {									\
+ 	__do_set_from_vec(struct hwentry, var, (src)->hwe, dest)
+ 
+ #define do_set_from_hwe(var, src, dest, msg)				\
+-	if (__do_set_from_hwe(var, src, dest)) {			\
++	if (!src->hwe) {						\
++		condlog(0, "BUG: do_set_from_hwe called with hwe == NULL"); \
++	} else if (__do_set_from_hwe(var, src, dest)) {			\
+ 		origin = msg;						\
+ 		goto out;						\
+ 	}
+-- 
+1.8.3.1
+

0025-libmultipath-fix-mpp-hwe-handling-in-sync_paths.patch

@@ -0,0 +1,44 @@
+From 44292f529f6c50e1abbab04acf7f0169094bdf24 Mon Sep 17 00:00:00 2001
+From: Martin Wilck <mwilck@suse.com>
+Date: Mon, 13 Jul 2020 13:07:43 +0200
+Subject: [PATCH 4/4] libmultipath: fix mpp->hwe handling in sync_paths()
+
+This is anologous to
+
+1f96269 ("multipathd: fix mpp->hwe handling on path removal")
+f6839eb ("multipathd: fix mpp->hwe handling when paths are freed")
+
+When paths are removed from a map, we need to make sure that
+mpp->hwe doesn't become stale.
+
+Reported-by: Lixiaokeng <lixiaokeng@huawei.com>
+Signed-off-by: Martin Wilck <mwilck@suse.com>
+---
+ libmultipath/structs_vec.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/libmultipath/structs_vec.c b/libmultipath/structs_vec.c
+index cde4dbe..ede1429 100644
+--- a/libmultipath/structs_vec.c
++++ b/libmultipath/structs_vec.c
+@@ -260,6 +260,8 @@ void sync_paths(struct multipath *mpp, vector pathvec)
+ 		}
+ 		if (!found) {
+ 			condlog(3, "%s dropped path %s", mpp->alias, pp->dev);
++			if (mpp->hwe == pp->hwe)
++				mpp->hwe = NULL;
+ 			vector_del_slot(mpp->paths, i--);
+ 			orphan_path(pp, "path removed externally");
+ 		}
+@@ -267,6 +269,8 @@ void sync_paths(struct multipath *mpp, vector pathvec)
+ 	update_mpp_paths(mpp, pathvec);
+ 	vector_foreach_slot (mpp->paths, pp, i)
+ 		pp->mpp = mpp;
++	if (mpp->hwe == NULL)
++		extract_hwe_from_path(mpp);
+ 
+ 	vector_foreach_slot (mpp->pg, pgp, i) {
+ 		vector_foreach_slot (pgp->paths, pp, j) {
+-- 
+1.8.3.1
+

multipath-tools.spec

@@ -1,6 +1,6 @@
 Name:    multipath-tools
 Version: 0.8.4
-Release: 1
+Release: 2
 Summary: Tools to manage multipath devices with the device-mapper
 License: GPLv2-or-later and LGPLv2+
 URL:     http://christophe.varoqui.free.fr/
@@ -29,6 +29,10 @@ Patch18: 0018-bugfix-clear-mpp-path-reference-when-path-is-freed-otherwis.patch
 Patch19: 0019-bugfix-libmultipath-fix-memory-leak-in-disassemble_map.patch
 Patch20: 0020-fix-find-multipath-failure.patch
 Patch21: 0021-change-kpartx-file-and-default-bindir.patch
+Patch22:0022-master-libmultipath-fix-use-after-free-when-iscsi-lo.patch
+Patch23:0023-libmultipath-warn-if-freeing-path-that-holds-mpp-hwe.patch
+Patch24:0024-libmultipath-warn-about-NULL-value-of-mpp-hwe.patch
+Patch25:0025-libmultipath-fix-mpp-hwe-handling-in-sync_paths.patch
 
 BuildRequires:    gcc, libaio-devel, userspace-rcu-devel, device-mapper-devel >= 1.02.89
 BuildRequires:    libselinux-devel, libsepol-devel, readline-devel, ncurses-devel, git
@@ -169,6 +173,12 @@ fi
 
 
 %changelog
+* Tue Sep 01 2020 lixiaokeng<lixiaokeng@huawei.com> - 0.8.4-2
+- Type:bugfix
+- ID:NA
+- SUG:NA
+- DESC:fix use after free in select_pgfailback
+
 * Thu Jul 16 2020 lixiaokeng <lixiaokeng@huawei.com> - 0.8.4-1
 - update to 0.8.4-1