CVE-2022-50818

In the Linux kernel, the following vulnerability has been resolved:

scsi: pm8001: Fix running_req for internal abort commands

Disabling the remote phy for a SATA disk causes a hang:

root@(none)$ more /sys/class/sas_phy/phy-0:0:8/target_port_protocols
sata
root@(none)$ echo 0 > sys/class/sas_phy/phy-0:0:8/enable
root@(none)$ [   67.855950] sas: ex 500e004aaaaaaa1f phy08 change count has changed
[   67.920585] sd 0:0:2:0: [sdc] Synchronizing SCSI cache
[   67.925780] sd 0:0:2:0: [sdc] Synchronize Cache(10) failed: Result: hostbyte=0x04 driverbyte=DRIVER_OK
[   67.935094] sd 0:0:2:0: [sdc] Stopping disk
[   67.939305] sd 0:0:2:0: [sdc] Start/Stop Unit failed: Result: hostbyte=0x04 driverbyte=DRIVER_OK
...
[  123.998998] INFO: task kworker/u192:1:642 blocked for more than 30 seconds.
[  124.005960]   Not tainted 6.0.0-rc1-205202-gf26f8f761e83 #218
[  124.012049] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  124.019872] task:kworker/u192:1  state:D stack:0 pid:  642 ppid: 2 flags:0x00000008
[  124.028223] Workqueue: 0000:04:00.0_event_q sas_port_event_worker
[  124.034319] Call trace:
[  124.036758]  __switch_to+0x128/0x278
[  124.040333]  __schedule+0x434/0xa58
[  124.043820]  schedule+0x94/0x138
[  124.047045]  schedule_timeout+0x2fc/0x368
[  124.051052]  wait_for_completion+0xdc/0x200
[  124.055234]  __flush_workqueue+0x1a8/0x708
[  124.059328]  sas_porte_broadcast_rcvd+0xa8/0xc0
[  124.063858]  sas_port_event_worker+0x60/0x98
[  124.068126]  process_one_work+0x3f8/0x660
[  124.072134]  worker_thread+0x70/0x700
[  124.075793]  kthread+0x1a4/0x1b8
[  124.079014]  ret_from_fork+0x10/0x20

The issue is that the per-device running_req read in
pm8001_dev_gone_notify() never goes to zero and we never make progress.
This is caused by missing accounting for running_req for when an internal
abort command completes.

In commit 2cbbf489778e ("scsi: pm8001: Use libsas internal abort support")
we started to send internal abort commands as a proper sas_task. In this
when we deliver a sas_task to HW the per-device running_req is incremented
in pm8001_queue_command(). However it is never decremented for internal
abort commnds, so decrement in pm8001_mpi_task_abort_resp().