Re: [PATCH v2 2/3] scsi: libiscsi: validate the ITT reflected in a Reject PDU

[Mike Christie <michael.christie@oracle.com>]

On 8/3/26 11:05 PM, Yehyeong Lee wrote:
> 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:
> 
>       memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
>       ...
>       task = iscsi_itt_to_task(conn, rejected_pdu.itt);
> 
> 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
> 
> Fixes: 8afa1439fcff ("[SCSI] libiscsi: handle immediate command rejections")
> Cc: stable@vger.kernel.org
> Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>

Reviewed-by: Mike Christie <michael.christie@oracle.com>