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mikechristiemartinkpetersen
mikechristie
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martinkpetersen
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scsi: iscsi_tcp: Fix UAF during logout when accessing the shost ipaddress
Bug report and analysis from Ding Hui. During iSCSI session logout, if another task accesses the shost ipaddress attr, we can get a KASAN UAF report like this: [ 276.942144] BUG: KASAN: use-after-free in _raw_spin_lock_bh+0x78/0xe0 [ 276.942535] Write of size 4 at addr ffff8881053b45b8 by task cat/4088 [ 276.943511] CPU: 2 PID: 4088 Comm: cat Tainted: G E 6.1.0-rc8+ #3 [ 276.943997] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 [ 276.944470] Call Trace: [ 276.944943] <TASK> [ 276.945397] dump_stack_lvl+0x34/0x48 [ 276.945887] print_address_description.constprop.0+0x86/0x1e7 [ 276.946421] print_report+0x36/0x4f [ 276.947358] kasan_report+0xad/0x130 [ 276.948234] kasan_check_range+0x35/0x1c0 [ 276.948674] _raw_spin_lock_bh+0x78/0xe0 [ 276.949989] iscsi_sw_tcp_host_get_param+0xad/0x2e0 [iscsi_tcp] [ 276.951765] show_host_param_ISCSI_HOST_PARAM_IPADDRESS+0xe9/0x130 [scsi_transport_iscsi] [ 276.952185] dev_attr_show+0x3f/0x80 [ 276.953005] sysfs_kf_seq_show+0x1fb/0x3e0 [ 276.953401] seq_read_iter+0x402/0x1020 [ 276.954260] vfs_read+0x532/0x7b0 [ 276.955113] ksys_read+0xed/0x1c0 [ 276.955952] do_syscall_64+0x38/0x90 [ 276.956347] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 276.956769] RIP: 0033:0x7f5d3a679222 [ 276.957161] Code: c0 e9 b2 fe ff ff 50 48 8d 3d 32 c0 0b 00 e8 a5 fe 01 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 [ 276.958009] RSP: 002b:00007ffc864d16a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 276.958431] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f5d3a679222 [ 276.958857] RDX: 0000000000020000 RSI: 00007f5d3a4fe000 RDI: 0000000000000003 [ 276.959281] RBP: 00007f5d3a4fe000 R08: 00000000ffffffff R09: 0000000000000000 [ 276.959682] R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000020000 [ 276.960126] R13: 0000000000000003 R14: 0000000000000000 R15: 0000557a26dada58 [ 276.960536] </TASK> [ 276.961357] Allocated by task 2209: [ 276.961756] kasan_save_stack+0x1e/0x40 [ 276.962170] kasan_set_track+0x21/0x30 [ 276.962557] __kasan_kmalloc+0x7e/0x90 [ 276.962923] __kmalloc+0x5b/0x140 [ 276.963308] iscsi_alloc_session+0x28/0x840 [scsi_transport_iscsi] [ 276.963712] iscsi_session_setup+0xda/0xba0 [libiscsi] [ 276.964078] iscsi_sw_tcp_session_create+0x1fd/0x330 [iscsi_tcp] [ 276.964431] iscsi_if_create_session.isra.0+0x50/0x260 [scsi_transport_iscsi] [ 276.964793] iscsi_if_recv_msg+0xc5a/0x2660 [scsi_transport_iscsi] [ 276.965153] iscsi_if_rx+0x198/0x4b0 [scsi_transport_iscsi] [ 276.965546] netlink_unicast+0x4d5/0x7b0 [ 276.965905] netlink_sendmsg+0x78d/0xc30 [ 276.966236] sock_sendmsg+0xe5/0x120 [ 276.966576] ____sys_sendmsg+0x5fe/0x860 [ 276.966923] ___sys_sendmsg+0xe0/0x170 [ 276.967300] __sys_sendmsg+0xc8/0x170 [ 276.967666] do_syscall_64+0x38/0x90 [ 276.968028] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 276.968773] Freed by task 2209: [ 276.969111] kasan_save_stack+0x1e/0x40 [ 276.969449] kasan_set_track+0x21/0x30 [ 276.969789] kasan_save_free_info+0x2a/0x50 [ 276.970146] __kasan_slab_free+0x106/0x190 [ 276.970470] __kmem_cache_free+0x133/0x270 [ 276.970816] device_release+0x98/0x210 [ 276.971145] kobject_cleanup+0x101/0x360 [ 276.971462] iscsi_session_teardown+0x3fb/0x530 [libiscsi] [ 276.971775] iscsi_sw_tcp_session_destroy+0xd8/0x130 [iscsi_tcp] [ 276.972143] iscsi_if_recv_msg+0x1bf1/0x2660 [scsi_transport_iscsi] [ 276.972485] iscsi_if_rx+0x198/0x4b0 [scsi_transport_iscsi] [ 276.972808] netlink_unicast+0x4d5/0x7b0 [ 276.973201] netlink_sendmsg+0x78d/0xc30 [ 276.973544] sock_sendmsg+0xe5/0x120 [ 276.973864] ____sys_sendmsg+0x5fe/0x860 [ 276.974248] ___sys_sendmsg+0xe0/0x170 [ 276.974583] __sys_sendmsg+0xc8/0x170 [ 276.974891] do_syscall_64+0x38/0x90 [ 276.975216] entry_SYSCALL_64_after_hwframe+0x63/0xcd We can easily reproduce by two tasks: 1. while :; do iscsiadm -m node --login; iscsiadm -m node --logout; done 2. while :; do cat \ /sys/devices/platform/host*/iscsi_host/host*/ipaddress; done iscsid | cat --------------------------------+--------------------------------------- |- iscsi_sw_tcp_session_destroy | |- iscsi_session_teardown | |- device_release | |- iscsi_session_release ||- dev_attr_show |- kfree | |- show_host_param_ | ISCSI_HOST_PARAM_IPADDRESS | |- iscsi_sw_tcp_host_get_param | |- r/w tcp_sw_host->session (UAF) |- iscsi_host_remove | |- iscsi_host_free | Fix the above bug by splitting the session removal into 2 parts: 1. removal from iSCSI class which includes sysfs and removal from host tracking. 2. freeing of session. During iscsi_tcp host and session removal we can remove the session from sysfs then remove the host from sysfs. At this point we know userspace is not accessing the kernel via sysfs so we can free the session and host. Link: https://lore.kernel.org/r/20230117193937.21244-2-michael.christie@oracle.com Signed-off-by: Mike Christie <michael.christie@oracle.com> Reviewed-by: Lee Duncan <lduncan@suse.com> Acked-by: Ding Hui <dinghui@sangfor.com.cn> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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-9
lines changed

3 files changed

+42
-9
lines changed

‎drivers/scsi/iscsi_tcp.c

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -983,10 +983,17 @@ static void iscsi_sw_tcp_session_destroy(struct iscsi_cls_session *cls_session)
983983
if (WARN_ON_ONCE(session->leadconn))
984984
return;
985985

986+
iscsi_session_remove(cls_session);
987+
/*
988+
* Our get_host_param needs to access the session, so remove the
989+
* host from sysfs before freeing the session to make sure userspace
990+
* is no longer accessing the callout.
991+
*/
992+
iscsi_host_remove(shost, false);
993+
986994
iscsi_tcp_r2tpool_free(cls_session->dd_data);
987-
iscsi_session_teardown(cls_session);
988995

989-
iscsi_host_remove(shost, false);
996+
iscsi_session_free(cls_session);
990997
iscsi_host_free(shost);
991998
}
992999

‎drivers/scsi/libiscsi.c

Lines changed: 31 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -3104,17 +3104,32 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
31043104
}
31053105
EXPORT_SYMBOL_GPL(iscsi_session_setup);
31063106

3107-
/**
3108-
* iscsi_session_teardown - destroy session, host, and cls_session
3109-
* @cls_session: iscsi session
3107+
/*
3108+
* issi_session_remove - Remove session from iSCSI class.
31103109
*/
3111-
void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
3110+
void iscsi_session_remove(struct iscsi_cls_session *cls_session)
31123111
{
31133112
struct iscsi_session *session = cls_session->dd_data;
3114-
struct module *owner = cls_session->transport->owner;
31153113
struct Scsi_Host *shost = session->host;
31163114

31173115
iscsi_remove_session(cls_session);
3116+
/*
3117+
* host removal only has to wait for its children to be removed from
3118+
* sysfs, and iscsi_tcp needs to do iscsi_host_remove before freeing
3119+
* the session, so drop the session count here.
3120+
*/
3121+
iscsi_host_dec_session_cnt(shost);
3122+
}
3123+
EXPORT_SYMBOL_GPL(iscsi_session_remove);
3124+
3125+
/**
3126+
* iscsi_session_free - Free iscsi session and it's resources
3127+
* @cls_session: iscsi session
3128+
*/
3129+
void iscsi_session_free(struct iscsi_cls_session *cls_session)
3130+
{
3131+
struct iscsi_session *session = cls_session->dd_data;
3132+
struct module *owner = cls_session->transport->owner;
31183133

31193134
iscsi_pool_free(&session->cmdpool);
31203135
kfree(session->password);
@@ -3132,10 +3147,19 @@ void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
31323147
kfree(session->discovery_parent_type);
31333148

31343149
iscsi_free_session(cls_session);
3135-
3136-
iscsi_host_dec_session_cnt(shost);
31373150
module_put(owner);
31383151
}
3152+
EXPORT_SYMBOL_GPL(iscsi_session_free);
3153+
3154+
/**
3155+
* iscsi_session_teardown - destroy session and cls_session
3156+
* @cls_session: iscsi session
3157+
*/
3158+
void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
3159+
{
3160+
iscsi_session_remove(cls_session);
3161+
iscsi_session_free(cls_session);
3162+
}
31393163
EXPORT_SYMBOL_GPL(iscsi_session_teardown);
31403164

31413165
/**

‎include/scsi/libiscsi.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -422,6 +422,8 @@ extern int iscsi_host_get_max_scsi_cmds(struct Scsi_Host *shost,
422422
extern struct iscsi_cls_session *
423423
iscsi_session_setup(struct iscsi_transport *, struct Scsi_Host *shost,
424424
uint16_t, int, int, uint32_t, unsigned int);
425+
void iscsi_session_remove(struct iscsi_cls_session *cls_session);
426+
void iscsi_session_free(struct iscsi_cls_session *cls_session);
425427
extern void iscsi_session_teardown(struct iscsi_cls_session *);
426428
extern void iscsi_session_recovery_timedout(struct iscsi_cls_session *);
427429
extern int iscsi_set_param(struct iscsi_cls_conn *cls_conn,

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