Subject: CVE-2021-47503: scsi: pm80xx: Do not call scsi_remove_host() in pm8001_alloc()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

scsi: pm80xx: Do not call scsi_remove_host() in pm8001_alloc()

Calling scsi_remove_host() before scsi_add_host() results in a crash:

 BUG: kernel NULL pointer dereference, address: 0000000000000108
 RIP: 0010:device_del+0x63/0x440
 Call Trace:
  device_unregister+0x17/0x60
  scsi_remove_host+0xee/0x2a0
  pm8001_pci_probe+0x6ef/0x1b90 [pm80xx]
  local_pci_probe+0x3f/0x90

We cannot call scsi_remove_host() in pm8001_alloc() because scsi_add_host()
has not been called yet at that point in time.

Function call tree:

  pm8001_pci_probe()
  |
  `- pm8001_pci_alloc()
  |  |
  |  `- pm8001_alloc()
  |     |
  |     `- scsi_remove_host()
  |
  `- scsi_add_host()

The Linux kernel CVE team has assigned CVE-2021-47503 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.10 with commit 05c6c029a44d and fixed in 5.10.85 with commit 1e434d2687e8
	Issue introduced in 5.10 with commit 05c6c029a44d and fixed in 5.15.8 with commit f8dccc1bdea7
	Issue introduced in 5.10 with commit 05c6c029a44d and fixed in 5.16 with commit 653926205741

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47503
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/scsi/pm8001/pm8001_init.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/1e434d2687e8bc0b3cdc9dd093c0e9047c0b4add
	https://git.kernel.org/stable/c/f8dccc1bdea7e21b5ec06c957aef8831c772661c
	https://git.kernel.org/stable/c/653926205741add87a6cf452e21950eebc6ac10b