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Date: Sun, 11 Dec 2022 10:54:17 +0800
From: dinghui <dinghui@...gfor.com.cn>
To: Mike Christie <michael.christie@...cle.com>, lduncan@...e.com,
cleech@...hat.com, jejb@...ux.ibm.com, martin.petersen@...cle.com,
open-iscsi@...glegroups.com, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] scsi: iscsi_tcp: Fix UAF when access shost attr during
session logout
On 2022/12/11 6:04 上午, Mike Christie wrote:
> On 12/9/22 2:22 AM, Ding Hui wrote:
>> During iscsi session logout, if another task accessing shost ipaddress
>> attr at this time, we can get a KASAN UAF report like this:
>>
>> [ 276.941685] ==================================================================
>> [ 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 |
>>
>> Since shost hold a pointer to session which is belong to cls_session by its
>> priv tcp_sw_host, so we should get a ref of cls_session, and after
>> iscsi_host_remove() the sysfs is cleared, then we can drop the ref.
>>
> Nice bug report and thanks for the patch. I think though we should just
> split the removal from the freeing. The removal will wait on users
> accessing sysfs files for us, so once they return we know we can just
> free things.
>
> Something like this:
I applied your patch, and it works well.
Since this is more reasonable, could you ignore mine and submit your
patch instead please? I appreciate it.
--
Thanks,
-dinghui
>
> diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
> index 5fb1f364e815..751e4b19798b 100644
> --- a/drivers/scsi/iscsi_tcp.c
> +++ b/drivers/scsi/iscsi_tcp.c
> @@ -982,10 +982,12 @@ static void iscsi_sw_tcp_session_destroy(struct iscsi_cls_session *cls_session)
> if (WARN_ON_ONCE(session->leadconn))
> return;
>
> + iscsi_session_remove(cls_session);
> + iscsi_host_remove(shost, false);
> +
> iscsi_tcp_r2tpool_free(cls_session->dd_data);
> - iscsi_session_teardown(cls_session);
>
> - iscsi_host_remove(shost, false);
> + iscsi_session_free(cls_session);
> iscsi_host_free(shost);
> }
>
> diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> index ef2fc860257e..235957de1164 100644
> --- a/drivers/scsi/libiscsi.c
> +++ b/drivers/scsi/libiscsi.c
> @@ -3104,17 +3104,27 @@ iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
> }
> EXPORT_SYMBOL_GPL(iscsi_session_setup);
>
> -/**
> - * iscsi_session_teardown - destroy session, host, and cls_session
> - * @cls_session: iscsi session
> +/*
> + * issi_session_remove - Remove session from iSCSI class.
> */
> -void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
> +void iscsi_session_remove(struct iscsi_cls_session *cls_session)
> {
> struct iscsi_session *session = cls_session->dd_data;
> - struct module *owner = cls_session->transport->owner;
> struct Scsi_Host *shost = session->host;
>
> iscsi_remove_session(cls_session);
> + iscsi_host_dec_session_cnt(shost);
> +}
> +EXPORT_SYMBOL_GPL(iscsi_session_remove);
> +
> +/**
> + * iscsi_session_free - Free iscsi session and it's resources
> + * @cls_session: iscsi session
> + */
> +void iscsi_session_free(struct iscsi_cls_session *cls_session)
> +{
> + struct iscsi_session *session = cls_session->dd_data;
> + struct module *owner = cls_session->transport->owner;
>
> iscsi_pool_free(&session->cmdpool);
> kfree(session->password);
> @@ -3132,10 +3142,19 @@ void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
> kfree(session->discovery_parent_type);
>
> iscsi_free_session(cls_session);
> -
> - iscsi_host_dec_session_cnt(shost);
> module_put(owner);
> }
> +EXPORT_SYMBOL_GPL(iscsi_session_free);
> +
> +/**
> + * iscsi_session_teardown - destroy session and cls_session
> + * @cls_session: iscsi session
> + */
> +void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
> +{
> + iscsi_session_remove(cls_session);
> + iscsi_session_free(cls_session);
> +}
> EXPORT_SYMBOL_GPL(iscsi_session_teardown);
>
> /**
> diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
> index 695eebc6f2c8..5cdeff776ce2 100644
> --- a/include/scsi/libiscsi.h
> +++ b/include/scsi/libiscsi.h
> @@ -422,6 +422,8 @@ extern int iscsi_host_get_max_scsi_cmds(struct Scsi_Host *shost,
> extern struct iscsi_cls_session *
> iscsi_session_setup(struct iscsi_transport *, struct Scsi_Host *shost,
> uint16_t, int, int, uint32_t, unsigned int);
> +extern void iscsi_session_remove(struct iscsi_cls_session *cls_session);
> +extern void iscsi_session_free(struct iscsi_cls_session *cls_session);
> extern void iscsi_session_teardown(struct iscsi_cls_session *);
> extern void iscsi_session_recovery_timedout(struct iscsi_cls_session *);
> extern int iscsi_set_param(struct iscsi_cls_conn *cls_conn,
>
>
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