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Subject[PATCH AUTOSEL 4.4 073/100] scsi: iscsi: Don't destroy session if there are outstanding connections
Date
From: Nick Black <nlb@google.com>

[ Upstream commit 54155ed4199c7aa3fd20866648024ab63c96d579 ]

A faulty userspace that calls destroy_session() before destroying the
connections can trigger the failure. This patch prevents the issue by
refusing to destroy the session if there are outstanding connections.

------------[ cut here ]------------
kernel BUG at mm/slub.c:306!
invalid opcode: 0000 [#1] SMP PTI
CPU: 1 PID: 1224 Comm: iscsid Not tainted 5.4.0-rc2.iscsi+ #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:__slab_free+0x181/0x350
[...]
[ 1209.686056] RSP: 0018:ffffa93d4074fae0 EFLAGS: 00010246
[ 1209.686694] RAX: ffff934efa5ad800 RBX: 000000008010000a RCX: ffff934efa5ad800
[ 1209.687651] RDX: ffff934efa5ad800 RSI: ffffeb4041e96b00 RDI: ffff934efd402c40
[ 1209.688582] RBP: ffffa93d4074fb80 R08: 0000000000000001 R09: ffffffffbb5dfa26
[ 1209.689425] R10: ffff934efa5ad800 R11: 0000000000000001 R12: ffffeb4041e96b00
[ 1209.690285] R13: ffff934efa5ad800 R14: ffff934efd402c40 R15: 0000000000000000
[ 1209.691213] FS: 00007f7945dfb540(0000) GS:ffff934efda80000(0000) knlGS:0000000000000000
[ 1209.692316] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1209.693013] CR2: 000055877fd3da80 CR3: 0000000077384000 CR4: 00000000000006e0
[ 1209.693897] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1209.694773] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1209.695631] Call Trace:
[ 1209.695957] ? __wake_up_common_lock+0x8a/0xc0
[ 1209.696712] iscsi_pool_free+0x26/0x40
[ 1209.697263] iscsi_session_teardown+0x2f/0xf0
[ 1209.698117] iscsi_sw_tcp_session_destroy+0x45/0x60
[ 1209.698831] iscsi_if_rx+0xd88/0x14e0
[ 1209.699370] netlink_unicast+0x16f/0x200
[ 1209.699932] netlink_sendmsg+0x21a/0x3e0
[ 1209.700446] sock_sendmsg+0x4f/0x60
[ 1209.700902] ___sys_sendmsg+0x2ae/0x320
[ 1209.701451] ? cp_new_stat+0x150/0x180
[ 1209.701922] __sys_sendmsg+0x59/0xa0
[ 1209.702357] do_syscall_64+0x52/0x160
[ 1209.702812] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1209.703419] RIP: 0033:0x7f7946433914
[...]
[ 1209.706084] RSP: 002b:00007fffb99f2378 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 1209.706994] RAX: ffffffffffffffda RBX: 000055bc869eac20 RCX: 00007f7946433914
[ 1209.708082] RDX: 0000000000000000 RSI: 00007fffb99f2390 RDI: 0000000000000005
[ 1209.709120] RBP: 00007fffb99f2390 R08: 000055bc84fe9320 R09: 00007fffb99f1f07
[ 1209.710110] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000038
[ 1209.711085] R13: 000055bc8502306e R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace a2d933ede7f730d8 ]---

Link: https://lore.kernel.org/r/20191226203148.2172200-1-krisman@collabora.com
Signed-off-by: Nick Black <nlb@google.com>
Co-developed-by: Salman Qazi <sqazi@google.com>
Signed-off-by: Salman Qazi <sqazi@google.com>
Co-developed-by: Junho Ryu <jayr@google.com>
Signed-off-by: Junho Ryu <jayr@google.com>
Co-developed-by: Khazhismel Kumykov <khazhy@google.com>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Co-developed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/iscsi_tcp.c | 4 ++++
drivers/scsi/scsi_transport_iscsi.c | 26 +++++++++++++++++++++++---
2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index fccb8991bd5b7..64a49dccb0b63 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -872,6 +872,10 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
static void iscsi_sw_tcp_session_destroy(struct iscsi_cls_session *cls_session)
{
struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);
+ struct iscsi_session *session = cls_session->dd_data;
+
+ if (WARN_ON_ONCE(session->leadconn))
+ return;

iscsi_tcp_r2tpool_free(cls_session->dd_data);
iscsi_session_teardown(cls_session);
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index ab32e60736424..20cf01d6ded7e 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -2965,6 +2965,24 @@ iscsi_set_path(struct iscsi_transport *transport, struct iscsi_uevent *ev)
return err;
}

+static int iscsi_session_has_conns(int sid)
+{
+ struct iscsi_cls_conn *conn;
+ unsigned long flags;
+ int found = 0;
+
+ spin_lock_irqsave(&connlock, flags);
+ list_for_each_entry(conn, &connlist, conn_list) {
+ if (iscsi_conn_get_sid(conn) == sid) {
+ found = 1;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&connlock, flags);
+
+ return found;
+}
+
static int
iscsi_set_iface_params(struct iscsi_transport *transport,
struct iscsi_uevent *ev, uint32_t len)
@@ -3539,10 +3557,12 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh, uint32_t *group)
break;
case ISCSI_UEVENT_DESTROY_SESSION:
session = iscsi_session_lookup(ev->u.d_session.sid);
- if (session)
- transport->destroy_session(session);
- else
+ if (!session)
err = -EINVAL;
+ else if (iscsi_session_has_conns(ev->u.d_session.sid))
+ err = -EBUSY;
+ else
+ transport->destroy_session(session);
break;
case ISCSI_UEVENT_UNBIND_SESSION:
session = iscsi_session_lookup(ev->u.d_session.sid);
--
2.20.1
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