In the Linux kernel, the following vulnerability has been resolved:
scsi: libiscsi: Validate the ITT reflected in a Reject PDU
A Reject PDU carries a copy of the header it rejects, and
iscsi_handle_reject() takes the ITT out of that copy to find the task to
clean up:
<pre>
memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
...
task = iscsi_itt_to_task(conn, rejected_pdu.itt);
</pre>
That value is whatever the target put there. iscsi_itt_to_task() bounds
the index against cmds_max and checks nothing else, so any task in the
pool can be named, and iscsi_nop_out_rsp() then completes it.
An index that has never been used gives a NULL task->conn: the pool is
zeroed at session setup and conn is assigned only when a task is
allocated. If the task was used and returned, iscsi_complete_task() hits
its WARN_ON_ONCE(task->state == ISCSI_TASK_FREE) and the refcount
underflows. An in-flight SCSI command is completed as successful - a 1
MiB read returned 1048576 with none of its buffer written and no
warning.
Validate the reflected ITT the way iscsi_itt_to_ctask() validates a
command ITT, and require the task to be in flight and not a SCSI
command.
[ 6.248477] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI
[ 6.249357] KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
[ 6.249951] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 7.2.0-rc5-ISCSI1-gf5098b6bae76 #1 PREEMPT(lazy)
[ 6.250718] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 6.251616] RIP: 0010:iscsi_nop_out_rsp.constprop.0+0x46/0x160
[ 6.252043] Code: c1 ea 03 48 83 ec 08 80 3c 02 00 0f 85 f5 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 58 48 8d 7d 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 00 00 00 48 8b 45 60 48 39 c3 74 50 48 b8 00
[ 6.252813] RSP: 0018:ffff88806c907b80 EFLAGS: 00010206
[ 6.253042] RAX: dffffc0000000000 RBX: ffff88800607e000 RCX: ffffffff8d571a25
[ 6.253345] RDX: 000000000000000c RSI: ffff88806c907c38 RDI: 0000000000000060
[ 6.253642] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff235a504
[ 6.253947] R10: 0000000000000003 R11: 7463656e6e6f6320 R12: 0000000000000000
[ 6.254251] R13: 0000000000000000 R14: ffff88806c907c38 R15: 0000000000000000
[ 6.254549] FS: 0000000000000000(0000) GS:ffff8880d95bc000(0000) knlGS:0000000000000000
[ 6.254887] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6.255140] CR2: 00007fc393e8ffc0 CR3: 0000000005252006 CR4: 0000000000770ef0
[ 6.255439] PKRU: 55555554
[ 6.255564] Call Trace:
[ 6.255674] <IRQ>
[ 6.255768] __iscsi_complete_pdu+0x18bf/0x22a0
[ 6.256733] iscsi_complete_pdu+0x54/0xa0
[ 6.256905] iscsi_tcp_data_recv_done+0xf4/0x250
[ 6.257103] iscsi_tcp_recv_skb+0x31e/0xec0
[ 6.257680] iscsi_sw_tcp_recv+0x12f/0x390
[ 6.258061] __tcp_read_sock+0x1ab/0x810
[ 6.258853] iscsi_sw_tcp_data_ready+0x18b/0x510
[ 6.259808] tcp_data_queue+0x1f13/0x4cd0
[ 6.260567] tcp_rcv_established+0x8a5/0x3a00
[ 6.261931] tcp_v4_do_rcv+0x449/0x960
[ 6.262269] tcp_v4_rcv+0x2245/0x3bc0
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 9.8
AV:N - A target-supplied ISCSI_OP_REJECT traverses iscsi_sw_tcp_data_ready(), iscsi_tcp_recv_skb(), iscsi_tcp_data_recv_done(), iscsi_complete_pdu(), and __iscsi_complete_pdu() to the patched iscsi_handle_reject(); the forged NOOP_OUT ITT is carried in the Reject PDU data over routable TCP.
AC:L - The target sees live SCSI ITTs in initiator commands and can withhold their responses before naming one in a forged Reject; alternatively, index 1 in a freshly bound kzalloc'ed pool deterministically has task->conn == NULL. No race or uncontrolled condition is required.
PR:N - iscsi_sw_tcp_conn_bind() installs receive callbacks before iscsi_conn_start() marks the session logged in, while __iscsi_complete_pdu() and iscsi_handle_reject() impose no login-state or authentication check on Reject PDUs. A target can therefore trigger the crash during login without credentials.
UI:N - Once a configured initiator binds or automatically reconnects its iSCSI socket, the target's Reject is processed directly by iscsi_sw_tcp_data_ready(); selecting an unused task slot requires no victim read, mount, or other action.
S:U - iscsi_handle_reject() corrupts task completion state or faults within the initiator host kernel; it does not cross a VM, IOMMU, or separate security-authority boundary.
C:H - For a READ ITT, iscsi_nop_out_rsp() reaches iscsi_complete_task() and scsi_done() with sc->result still zero despite no Data-In; non-zeroed page-cache folios can consequently be marked uptodate and exposed as valid data, with the commit demonstrating a 1 MiB untouched read.
I:H - The unchecked ITT lets iscsi_nop_out_rsp() falsely complete any observed in-flight SCSI task successfully; untouched READ buffers become valid filesystem data and WRITE commands can be acknowledged without commitment, permitting silent persistent storage or filesystem corruption.
A:H - Selecting a never-used pool slot returns a task whose kzalloc'ed task->conn is NULL, which iscsi_nop_out_rsp() dereferences; the commit records the resulting general-protection fault, so one crafted Reject can oops or panic the host.
| Attack Vector |
Network |
Scope |
Unchanged |
| Attack Complexity |
Low |
Confidentiality Impact |
High |
| Privileges Required |
None |
Integrity Impact |
High |
| User Interaction |
None |
Availability Impact |
High |
AV:N - A target-supplied ISCSI_OP_REJECT traverses iscsi_sw_tcp_data_ready(), iscsi_tcp_recv_skb(), iscsi_tcp_data_recv_done(), iscsi_complete_pdu(), and __iscsi_complete_pdu() to the patched iscsi_handle_reject(); the forged NOOP_OUT ITT is carried in the Reject PDU data over routable TCP.
AC:L - The target sees live SCSI ITTs in initiator commands and can withhold their responses before naming one in a forged Reject; alternatively, index 1 in a freshly bound kzalloc'ed pool deterministically has task->conn == NULL. No race or uncontrolled condition is required.
PR:N - iscsi_sw_tcp_conn_bind() installs receive callbacks before iscsi_conn_start() marks the session logged in, while __iscsi_complete_pdu() and iscsi_handle_reject() impose no login-state or authentication check on Reject PDUs. A target can therefore trigger the crash during login without credentials.
UI:N - Once a configured initiator binds or automatically reconnects its iSCSI socket, the target's Reject is processed directly by iscsi_sw_tcp_data_ready(); selecting an unused task slot requires no victim read, mount, or other action.
S:U - iscsi_handle_reject() corrupts task completion state or faults within the initiator host kernel; it does not cross a VM, IOMMU, or separate security-authority boundary.
C:H - For a READ ITT, iscsi_nop_out_rsp() reaches iscsi_complete_task() and scsi_done() with sc->result still zero despite no Data-In; non-zeroed page-cache folios can consequently be marked uptodate and exposed as valid data, with the commit demonstrating a 1 MiB untouched read.
I:H - The unchecked ITT lets iscsi_nop_out_rsp() falsely complete any observed in-flight SCSI task successfully; untouched READ buffers become valid filesystem data and WRITE commands can be acknowledged without commitment, permitting silent persistent storage or filesystem corruption.
A:H - Selecting a never-used pool slot returns a task whose kzalloc'ed task->conn is NULL, which iscsi_nop_out_rsp() dereferences; the commit records the resulting general-protection fault, so one crafted Reject can oops or panic the host.
CVSS 3.1